Apparatus and method for communication using sidelink in wireless communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The disclosure is to configure configuration parameter information of a sidelink radio bearer in a wireless communication system. An operation of a terminal may include: determining whether there is a need of an SLRB configuration; obtaining the SLRB configuration; performing sidelink data transmission or reception by using the SLRB configuration; determining whether there is a collision of the SLRB configuration; and performing a procedure of adjusting the collision of the SLRB configuration.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. 119 toKorean Patent Application No. 10-2019-0142691, filed on Nov. 8, 2019, inthe Korean Intellectual Property Office, the disclosure of which isherein incorporated by reference in its entirety.

BACKGROUND 1. Field

The disclosure relates to a method and an apparatus for a communicationusing sidelink in a wireless communication system. The disclosurerelates, more specifically, to an apparatus and a method for processingsidelink radio bearer configuration information in a wirelesscommunication system. Also, the disclosure relates to a method and anapparatus for configuring sidelink radio bearer information in awireless communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (millimeter Wave or “mmWave”) bands,e.g., 60 giga-Hertz (GHz) bands, so as to accomplish higher data rates.To decrease propagation loss of the radio waves and increase thetransmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems. In addition, in 5G communication systems,development for system network improvement is under way based onadvanced small cells, cloud Radio Access Networks (RANs), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving network, cooperative communication, Coordinated Multi-Points(CoMP), reception-end interference cancellation and the like. In the 5Gsystem, Hybrid FSK and QAM Modulation (FQAM) and sliding windowsuperposition coding (SWSC) as an advanced coding modulation (ACM), andfilter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA),and sparse code multiple access (SCMA) as an advanced access technologyhave been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

Furthermore, terminal-to-terminal direct communication (sidelinkcommunication) using a 5G communication system has been studied. Theterminal-to-terminal direct communication is expected to be applied to,for example, vehicle communication (vehicle-to-everything, hereinafter,“V2X”) and provide various services to a user.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

In accordance with the above discussion, the disclosure provides anapparatus and a method for processing sidelink configuration informationin a wireless communication system.

In addition, the disclosure provides an apparatus and a method forconfiguring radio bearer configuration information between terminalsperforming transmission or reception, based on sidelink unicast,sidelink groupcast, and sidelink broadcast in a wireless communicationsystem.

According to various embodiments, an operation method of a terminal in awireless communication system may include: determining whether there isa need to obtain a sidelink radio bearer (SLRB) configuration; obtainingthe SLRB configuration from a network (NW) or a system; and performingsidelink data transmission or reception with an opposite terminal of asidelink unicast by using the obtained SLRB configuration.

In addition, the operation method of the terminal according to variousembodiments may include: determining whether there is a collisionbetween SLRB configurations; and if it is determined that there is acollision between the SLRB configurations, determining failure of asidelink unicast configuration procedure.

In addition, the operation method of the terminal according to variousembodiments may include: determining whether there is a collisionbetween SLRB configurations; determining whether there is a need toadjust a collided configuration parameter; and performing aconfiguration parameter adjustment procedure.

In addition, the operation method of the terminal according to variousembodiments may include: if it is determined that there is a need toadjust the SLRB configuration, reporting the need to the NW; andidentifying a configuration parameter of the NW.

In addition, a terminal in a wireless communication system according tovarious embodiments includes: a transceiver; and at least one processorconnected to the transceiver. The at least one processor may: determinewhether there is a need to obtain an SLRB configuration; obtain the SLRBconfiguration; transmit or receive sidelink data by using the SLRBconfiguration; determine whether there is a need to adjust an SLRBconfiguration parameter; and perform a procedure of adjusting the SLRBconfiguration parameter.

In addition, according to an embodiment of the disclosure, a methodperformed by a first terminal is provided. The method comprisesreceiving, from a second terminal, a first message including a sidelinkradio bearer (SLRB) configuration, identifying a failure of an accessstratum (AS) configuration based on the SLRB configuration andtransmitting, to the second terminal, a second message includinginformation indicating the failure of the AS configuration, in case thatthe failure of the AS configuration is identified.

In addition, according to an embodiment of the disclosure, a methodperformed by a second terminal is provided. The method comprisestransmitting, to a first terminal, a first message including a sidelinkradio bearer (SLRB) configuration, receiving, from the first terminal, asecond message as a response to the second message, and identifying afailure of an access stratum (AS) configuration based on the SLRBconfiguration in case that information indicating the failure of the ASconfiguration is included in the second message.

Through an apparatus and a method according to various embodiments, theproblem of terminal operation errors caused by a mismatch inconfiguration information between terminals performing directcommunication, and the problem of service quality degradation caused byservice interruption can be effectively resolved.

Effects which can be acquired by the disclosure are not limited to theabove described effects, and other effects that have not been mentionedmay be clearly understood by those skilled in the art from the followingdescription.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosure and its advantages,reference is now made to the following description taken in conjunctionwith the accompanying drawings, in which like reference numeralsrepresent like parts:

FIG. 1 illustrates a wireless communication system according to variousembodiments;

FIG. 2 illustrates a configuration of a base station in a wirelesscommunication system according to various embodiments;

FIG. 3 illustrates a configuration of a terminal in a wirelesscommunication system according to various embodiments;

FIG. 4 illustrates a configuration of a communication unit in a wirelesscommunication system according to various embodiments;

FIG. 5 illustrates a structure of wireless time-frequency resources of awireless communication system according to various embodiments;

FIG. 6A illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments;

FIG. 6B illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments;

FIG. 6C illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments;

FIG. 6D illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments;

FIG. 7A illustrates an example of a sidelink communication transmissionscheme in a wireless communication system according to variousembodiments;

FIG. 7B illustrates an example of a sidelink communication transmissionscheme in a wireless communication system according to variousembodiments;

FIG. 8A illustrates a signal flow diagram between terminals using a NWcoordination method according to various embodiments, and FIG. 8B is asignal flow diagram between terminals using a NW coordination methodaccording to various embodiments;

FIG. 9 illustrates a method of selecting a terminal deciding an SLRBconfiguration according to various embodiments;

FIG. 10A illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 10B illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 11 illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 12 illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 13 illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 14 illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 15A illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 15B illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 15C illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments;

FIG. 16A illustrates an SLRB configuration coordination method usingbase station cooperation according to various embodiments;

FIG. 16B illustrates an SLRB configuration coordination method usingbase station cooperation according to various embodiments;

FIG. 17A illustrates an SLRB configuration coordination method usingbase station cooperation according to various embodiments;

FIG. 17B illustrates an SLRB configuration coordination method usingbase station cooperation according to various embodiments;

FIG. 18 illustrates an SLRB configuration coordination method using basestation cooperation according to various embodiments;

FIG. 19 is a signal flow diagram for processing SLRB configurationprocessing failure according to various embodiments; and

FIG. 20 is a signal flow diagram between terminals processing acollision between SLRB configurations according to various embodiments.

DETAILED DESCRIPTION

FIGS. 1 through 20 , discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The terms used in the disclosure are only used to describe specificembodiments, and are not intended to limit the disclosure. A singularexpression may include a plural expression unless they are definitelydifferent in a context. Unless defined otherwise, all terms used herein,including technical and scientific terms, have the same meaning as thosecommonly understood by a person skilled in the art to which thedisclosure pertains. Such terms as those defined in a generally useddictionary may be interpreted to have the meanings equal to thecontextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the disclosure. In some cases, even the term defined in thedisclosure should not be interpreted to exclude embodiments of thedisclosure.

Hereinafter, various embodiments of the disclosure will be describedbased on an approach of hardware. However, various embodiments of thedisclosure include a technology that uses both hardware and software,and thus the various embodiments of the disclosure may not exclude theperspective of software.

Hereinafter, the disclosure relates to an apparatus and a method forprocessing sidelink configuration information in a wirelesscommunication system. Specifically, the disclosure is to configure abi-directional radio bearer or a uni-directional radio bearer insidelink communication between a terminal and a terminal, and thedisclosure relates to an apparatus and a method wherein a piece ofconfiguration information, which is required to be matched between thetwo terminals, among pieces of configuration information of a radiobearer between the terminals may be processed.

In the disclosure, sidelink configuration information may be, forexample, configuration information of a sidelink radio bearer, and mayinclude configuration information for processing at least one of asignaling radio bearer and a data radio bearer. Specifically, theconfiguration information may include at least one of PDCP layerconfiguration information, RLC layer configuration information, MAClayer configuration information, and physical layer configurationinformation of a signaling radio bearer with which sidelink RRCsignaling or sidelink PC5-S signaling is transmitted. The configurationinformation may include at least one of SDAP layer configurationinformation, PDCP layer configuration information, RLC layerconfiguration information, MAC layer configuration information, andphysical layer configuration information of a data radio bearer withwhich sidelink user data is transmitted.

In the following description, a term indicating a signal, a termindicating a channel, a term indicating control information, termsindicating network entities, terms indicating elements of a device, andthe like are exemplified for convenience of explanation. Accordingly,the disclosure is not limited to the following terms and other termshaving the same technical meaning may be used.

In the following description, a physical channel and a signal may beused together with data or a control signal. For example, a physicaldownlink shared channel (PDSCH) is a term indicating a physical channelthrough which data is transmitted, but a PDSCH may be also used toindicate data. That is, in the disclosure, the expression “transmit aphysical channel” may be interpreted equivalent to the expression“transmit data or a signal through a physical channel”.

Hereinafter, in the disclosure, higher signaling means a signal transfermethod by which a signal is transferred to a terminal by a base stationby using a physical layer downlink data channel, or a signal istransferred to a base station by a terminal by using a physical layeruplink data channel. Higher signaling may be interpreted as radioresource control (RRC) signaling or a media access control (MAC) controlelement (CE).

In addition, in the disclosure, although the expression “more than” or“less than” is used in order to determine whether or not a particularcondition is fulfilled or satisfied, this is only an example and doesnot exclude the expression “equal to or more than” or “equal to or lessthan”. The expression “equal to or more than” can be replaced with “morethan”, the expression “equal to or less than” can be replaced with “lessthan”, and the expression “equal to or more than and less than” can bereplaced with “more than and equal to or less than” under the conditionsabove.

In addition, the disclosure includes terms used in some communicationprotocols (e.g. 3rd generation partnership project (3GPP)) to explainvarious embodiments, but the terms merely correspond to examples.Various embodiments may also be easily modified and then applied toother communication systems.

FIG. 1 illustrates a wireless communication system according to variousembodiments.

FIG. 1 illustrates a base station 110, a terminal 120, and a terminal130 as a part of nodes using wireless channels in a wirelesscommunication system. Although, FIG. 1 illustrates only one basestation, another base station identical to or similar to the basestation 110 may be further included.

The base station 110 is a network infrastructure that provides wirelessconnection to the terminals 120 and 130. The base station 110 has acoverage defined as a particular geographic area based on a distance bywhich the base station can transmit a signal. The base station 110 maybe called “an access point (AP)”, “an eNodeB (eNB)”, “a 5th generationnode”, “an gNodeB (a next generation node B; gNB)”, “a wireless point”,“a transmission/reception point (TRP)” or other terms having a technicalmeaning equivalent thereto.

Each of the terminals 120 and 130 is a device used by a user andcommunicates with the base station 110 through wireless channels. A linkoriented from the base station 110 to the terminal 120 or 130 isreferred to as a downlink (DL), and a link oriented from the terminal120 or 130 to the base station 110 is referred to as an uplink (UL). Inaddition, the terminals 120 and 130 may perform communication with eachother through a wireless channel. The link between the terminals 120 and130 is called a sidelink, and a sidelink may be used together with a PC5interface. In some cases, at least one of the terminals 120 and 130 maybe operated without involvement of a user. That is, at least one of theterminals 120 and 130 is a device configured to perform machine-typecommunication (MTC) and may not be carried by a user. Each of theterminals 120 and 130 may be called “a user equipment (UE)”, “a mobilestation”, “a subscriber station”, “a remote terminal”, “a wirelessterminal”, “a user device”, or another term having a technical meaningequivalent thereto.

The base station 110 and the terminals 120 and 130 may transmit andreceive a wireless signal in millimeter wave (mmWave) bands (e.g. 28GHz, 30 GHz, 38 GHz, and 60 GHz). To improve a channel gain, the basestation 110 and the terminals 120 and 130 may perform beamforming.Beamforming may include transmission beamforming and receptionbeamforming. That is, the base station 110 and the terminals 120 and 130may give directivity to a transmission signal or a reception signal. Tothis end, the base station 110 and the terminals 120 and 130 may selectserving beams 112, 113, 121, and 131 through a beam search procedure ora beam management procedure. Communication after the serving beams 112,113, 121, and 131 are selected may be performed through resources havinga quasi-co-located (QCL) relationship with resources used fortransmission of the serving beams 112, 113, 121, and 131.

If large-scale characteristics of a channel having transferred a symbolon a first antenna port can be inferred from a channel havingtransferred a symbol on a second antenna port, the first antenna portand the second antenna port may be considered to have a QCL relationshiptherebetween. For example, the large-scale characteristics may includeat least one of delay spread, Doppler spread, Doppler shift, averagegain, average delay, and spatial receiver parameter.

The terminals 120 and 130 illustrated in FIG. 1 may support vehiclecommunication. In a case of vehicle communication, a standardizationwork for V2X technology has been completed in 3GPP release 14 and 15,based on a device-to-device (D2D) communication structure in an LTEsystem. Currently, work is being done in developing V2X technology,based on 5G NR. NR V2X will support terminal-to-terminal unicastcommunication, groupcast (or multicast) communication, and broadcastcommunication. In addition, unlike LTE V2X aiming to transmit andreceive basic safety information required for road driving of a vehicle,NR V2X aims to provide further-evolved services such as platooning,advanced driving, sensing by an extended sensor, and remote driving.

A V2X service may be divided into a basic safety service and an advancedservice. The basic safety service may include a detailed service such asa car notification (cooperative awareness messages (CAMs) or basicsafety messages (BSMs)) service, a left-turn notification service, afront-car collision warning service, an emergency car accessnotification service, a front obstacle warning service, and anintersection traffic light information service. V2X information may betransmitted or received using a broadcast, unicast, or groupcasttransmission scheme. The advanced service not only has enhanced qualityof service (QoS) requirements compared to the basic safety service, butalso requires a method for transmitting or receiving V2X information byusing unicast and groupcast transmission schemes rather than a broadcasttransmission scheme, so as to allow V2X information to be transmitted orreceived in a particular vehicle group or between two vehicles. Theadvanced service may include a detailed service such as a platooningservice, a self-driving service, a remote driving service, and anextended sensor-based V2X service.

Hereinafter, a sidelink (SL) indicates a signal transmission/receptionpath between terminals, and may be used together with a PC5 interface.Hereinafter, a base station is a subject performing terminal resourceallocation, and may support both V2X communication and general cellularcommunication, or only V2X communication. That is, a base station mayimply an NR base station (e.g. gNB), an LTE base station (e.g. eNB), ora road site unit (RSU). A terminal may include not only a general userequipment and a mobile station but also all of a vehicle supportingvehicular-to-vehicular (V2V) communication, a vehicle or a pedestrian'shandset (e.g. smartphone) supporting vehicular-to-pedestrian (V2P)communication, a vehicle supporting vehicular-to-network (V2N)communication, or a vehicle supporting communication between a vehicleand a transportation infrastructure (vehicular-to-infrastructure (V21)communication), and an RSU equipped with a terminal function, an RSUequipped with a base station function, or an RSU equipped with a part ofa base station function and a part of a terminal function. In addition,a V2X terminal used in the following description may be referred to as aterminal. That is, a terminal may be used as a V2X terminal in relationto V2X communication.

A base station and a terminal are connected to each other through a Uuinterface. An uplink (UL) may imply a wireless link through which aterminal transmits data or a control signal to a base station, and adownlink (DL) may imply a wireless link through which a base stationtransmits data or a control signal to a terminal.

FIG. 2 illustrates a configuration of a base station in a wirelesscommunication system according to various embodiments. The configurationillustrated in FIG. 2 may be understood as a configuration of the basestation 110. The term “ . . . unit” or the ending of a word, such as “ .. . or”, “ . . . er”, or the like used hereinafter may indicate a unitof processing at least one function or operation, and this may beembodied by hardware, software, or a combination of hardware andsoftware.

Referring to FIG. 2 , the base station 110 includes a wirelesscommunication unit 210, a backhaul communication unit 220, a storageunit 230, and a controller 240.

The wireless communication unit 210 performs functions for transmittingor receiving a signal through a wireless channel. For example, thewireless communication unit 210 performs a function of conversionbetween a baseband signal and a bit stream according to a physical layerprotocol of the system. For example, when data is transmitted, thewireless communication unit 210 generates complex symbols by encodingand modulating a transmission bit stream. Furthermore, when data isreceived, the wireless communication unit 210 reconstructs a receptionbit stream by demodulating and decoding a baseband signal.

Furthermore, the wireless communication unit 210 up-converts a basebandsignal into a radio-frequency (RF) band signal and then transmits theconverted RF band signal through an antenna, and down-converts an RFband signal received through an antenna into a baseband signal. To thisend, the wireless communication unit 210 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, adigital-to-analog converter (DAC), an analog-to-digital converter (ADC),and the like. In addition, the wireless communication unit 210 mayinclude a plurality of transmission/reception paths. Furthermore, thewireless communication unit 210 may include at least one antenna arrayconfigured by multiple antenna elements.

In view of hardware, the wireless communication unit 210 may beconfigured by a digital unit and an analog unit, and the analog unit mayinclude a plurality of sub-units according to operating power, operatingfrequency, etc. The digital unit may be implemented as at least oneprocessor (e.g. a digital signal processor (DSP)).

The wireless communication unit 210 transmits and receives a signal asdescribed above. Accordingly, the entirety or a part of the wirelesscommunication unit 210 may be called “a transmitter”, “a receiver”, or“a transceiver”. Furthermore, in the following description, transmissionand reception through a wireless channel may be understood to includethe aforementioned processing of the wireless communication unit 210.

The backhaul communication unit 220 provides an interface for performingcommunication with other nodes within a network. That is, the backhaulcommunication unit 220 converts, into a physical signal, a bit streamtransmitted from the base station 110 to another node, for example,another access node, another base station, a higher node, a corenetwork, etc., and converts a physical signal received from another nodeinto a bit stream.

The storage unit 230 stores data such as a basic program, an applicationprogram, and configuration information for the operation of the basestation 110. The storage unit 230 may be configured as a volatilememory, a nonvolatile memory, or a combination of a volatile memory anda nonvolatile memory. The storage unit 230 provides stored data inresponse to a request of the controller 240.

The controller 240 controls overall operations of the base station 110.For example, the controller 240 transmits and receives a signal throughthe wireless communication unit 210 or the backhaul communication unit220. Further, the controller 240 records and reads data in and from thestorage unit 230. In addition, the controller 240 may perform functionsof a protocol stack required in a communication protocol. According toanother embodiment, a protocol stack may be included in the wirelesscommunication unit 210. To this end, the controller 240 may include atleast one processor. According to various embodiments, the controller240 may control the base station 110 to perform operations according tovarious embodiments described later.

FIG. 3 illustrates a configuration of a terminal in a wirelesscommunication system according to various embodiments.

The configuration illustrated in FIG. 3 may be understood as aconfiguration of the terminal 120. The term “ . . . unit” or the endingof a word, such as “ . . . or”, “ . . . er”, or the like usedhereinafter may indicate a unit of processing at least one function oroperation, and this may be embodied by hardware, software, or acombination of hardware and software.

Referring to FIG. 3 , the terminal 120 includes a communication unit310, a storage unit 320, and a controller 330.

The communication unit 310 performs functions for transmitting orreceiving a signal through a wireless channel. For example, thecommunication unit 310 performs a function of conversion between abaseband signal and a bit stream according to a physical layer protocolof the system. For example, when data is transmitted, the communicationunit 310 generates complex symbols by encoding and modulating atransmission bit stream. Furthermore, when data is received, thecommunication unit 310 reconstructs a reception bit stream bydemodulating and decoding a baseband signal. Furthermore, thecommunication unit 310 up-converts a baseband signal into an RF bandsignal and then transmits the converted RF band signal through anantenna, and down-converts an RF band signal received through an antennainto a baseband signal. For example, the communication unit 310 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a DAC, an ADC, and the like.

In addition, the communication unit 310 may include a plurality oftransmission/reception paths. Furthermore, the communication unit 310may include at least one antenna array including a plurality of antennaelements. In view of hardware, the communication unit 310 may beconfigured by a digital circuit and an analog circuit (e.g.radio-frequency integrated circuit (RFIC)). The digital circuit and theanalog circuit may be implemented as a single package. In addition, thecommunication unit 310 may include a plurality of RF chains. Moreover,the communication unit 310 may perform beamforming.

The communication unit 310 transmits and receives a signal as describedabove. Accordingly, the entirety or a part of the communication unit 310may be called “a transmitter”, “a receiver”, or “a transceiver”. Inaddition, in the following description, transmission and receptionthrough a wireless channel may be understood to include the processingperformed by the communication unit 310, as described above.

The storage unit 320 stores data such as a basic program, an applicationprogram, and configuration information for the operation of the terminal120. The storage unit 320 may be configured as a volatile memory, anonvolatile memory, or a combination of a volatile memory and anonvolatile memory. The storage unit 320 provides stored data inresponse to a request of the controller 330.

The controller 330 controls overall operations of the terminal 120. Forexample, the controller 330 transmits and receives a signal through thecommunication unit 310. In addition, the controller 330 records andreads data in and from the storage unit 320. Moreover, the controller330 may perform functions of a protocol stack required in acommunication protocol. To this end, the controller 330 may include atleast one processor or microprocessor, or may be a part of a processor.In addition, the controller 330 and a part of the communication unit 310may be called a communication processor (CP). According to variousembodiments, the controller 330 may control the terminal 120 to performoperations according to various embodiments described later.

According to various embodiments of the disclosure, the controller 330is configured to a controller configured to receive, from a secondterminal via the transceiver, a first message including sidelink radiobearer (SLRB) configuration, to identify a failure of an access stratum(AS) configuration based on the SLRB configuration, and to transmit, tothe second terminal via the transceiver, a second message includinginformation indicating the failure of the AS configuration, in case thatthe failure of the AS configuration is identified.

The SLRB configuration includes at least one of a radio link control(RLC) mode or a logical channel identity associated with the RLC mode,and the failure of the AS configuration is identified based on the RLCmode. Also, the failure of the AS configuration is identified based onthe SLRB configuration received from the second terminal and anotherSLRB configuration received from a base station.

The controller 330 is configured to transmit, to a base station via thetransceiver, sidelink terminal information including at least oneinformation included in the SLRB configuration as a response to thefirst message, and to receive, from the base station via thetransceiver, a radio resource control (RRC) reconfiguration messageincluding new SLRB configuration associated with the SLRB configuration.Also, the sidelink terminal information includes an RLC mode orparameters associated with the RLC mode, the RLC mode and the parametersassociated with the RLC mode being included in the SLRB configuration,and a third message indicating the application of the SLRB configurationis transmitted to the second terminal, in case that the failure of theAS configuration is not identified based on the RRC reconfiguration.

According to various embodiments of the disclosure, the controller 330is configured to transmit, to a first terminal via the transceiver, afirst message including a sidelink radio bearer (SLRB) configuration, toreceive, from the first terminal via the transceiver, a second messageas a response to the second message, and to identify a failure of anaccess stratum (AS) configuration based on the SLRB configuration incase that information indicating the failure of the AS configuration isincluded in the second message. Also, the SLRB configuration includes atleast one of a radio link control (RLC) mode or a logical channelidentity associated with the RLC mode, and wherein the failure of the ASconfiguration is identified based on the RLC mode.

The controller 330 is configured to transmit, to a base station via thetransceiver, sidelink terminal information including the informationindicating the failure of the AS configuration, in case that the failureof the AS configuration is identified. The sidelink terminal informationfurther includes a sidelink destination identity associated with thefailure of the AS configuration. Also, a timer is started as a responseto a transmission of the first message, the timer is stopped as aresponse to a reception of the second message, and wherein a procedurefor the AS configuration associated with the first terminal is stoppedin case that the information indicating the failure of the ASconfiguration is included in the second message.

FIG. 4 illustrates a configuration of a communication unit in a wirelesscommunication system according to various embodiments.

FIG. 4 illustrates an example of a specific configuration of thewireless communication unit 210 illustrated in FIG. 2 or thecommunication unit 310 illustrated in FIG. 3 . Specifically, FIG. 4illustrates elements performing beamforming, which are a part of thewireless communication unit 210 in FIG. 2 or the communication unit 310in FIG. 3 .

Referring to FIG. 4 , the wireless communication unit 210 or thecommunication unit 310 includes an encoding-and-modulating unit 402, adigital beamforming unit 404, a plurality of transmission paths 406-1 to406-N, and an analog beamforming unit 408.

The encoding-and-modulating unit 402 performs channel encoding. Forchannel encoding, at least one of a low density parity check (LDPC)code, a convolution code, and a polar code may be used. Theencoding-and-modulating unit 402 generates modulation symbols byperforming constellation mapping.

The digital beamforming unit 404 performs beamforming on a digitalsignal (e.g. modulation symbols). To this end, the digital beamformingunit 404 multiplies beamforming weights to the modulation symbols.Beamforming weights are used for changing the size and the phase of asignal, and may be called “a precoding matrix”, “a precoder”, etc. Thedigital beamforming unit 404 outputs, to the plurality of transmissionpaths 406-1 to 406-N, the modulation symbols, which have been subjectedto digital beamforming. According to a multiple input multiple output(MIMO) transmission scheme, the modulation symbols may be multiplexed,or the same modulation symbols may be provided to the plurality oftransmission paths 406-1 to 406-N.

The plurality of transmission paths 406-1 to 406-N convert, into analogsignals, digital signals having been subjected to digital beamforming.To this end, each of the plurality of transmission paths 406-1 to 406-Nmay include an inverse fast Fourier transform (IFFT) calculator, acyclic prefix (CP) insertion unit, a DAC, and an up converter. The CPinsertion unit is designed for an orthogonal frequency divisionmultiplexing (OFDM) scheme, and may be excluded in another physicallayer scheme (e.g. filter bank multi-carrier (FBMC)). That is, theplurality of transmission paths 406-1 to 406-N provide independentsignal processing processes for multiple streams generated throughdigital beamforming, respectively. However, according to animplementation method, a part of the elements of the plurality oftransmission paths 406-1 to 406-N may be shared.

The analog beamforming unit 408 performs beamforming on an analogsignal. To this end, the digital beamforming unit 404 multipliesbeamforming weights to analog signals. The beamforming weights are usedfor changing the size and the phase of a signal. Specifically, accordingto a connection structure between the plurality of transmission paths406-1 to 406-N and antennas, the analog beamforming unit 440 may bevariously configured. For example, each of the plurality of transmissionpaths 406-1 to 406-N may be connected to one antenna array. As anotherexample, the plurality of transmission paths 406-1 to 406-N may beconnected to one antenna array. As yet other example, the plurality oftransmission paths 406-1 to 406-N may be adaptively connected to oneantenna array or two or more antenna arrays.

FIG. 5 illustrates a structure of wireless time-frequency resources of awireless communication system according to various embodiments.

Referring to FIG. 5 , in the wireless resource region, the horizontalaxis indicates a time domain and the vertical axis indicates a frequencydomain. In the time domain, a minimum transmission unit is an OFDMsymbol or a DFT-S-OFDM symbol, and Nsymb number of OFDM symbols orDFT-S-OFDM symbols 530 may be included in one slot 505. Unlike a slot,in an NR system, the length of a subframe may be defined as 1.0milliseconds (ms), and the length of a radio frame 500 may be defined as10 ms. In the frequency domain, a minimum transmission unit is asubcarrier, and the bandwidth of the entire system transmission band mayinclude a total of NBW subcarriers 525. Specific numerical values forNsymb, NBW, or the like may be variably applied according to a system.

A basic unit of the time-frequency resource region is a resource element(RE) 510 which may be represented by an OFDM symbol index or DFT-S-OFDMsymbol index, and a subcarrier index. A resource block (RB) 515 may bedefined as NRB number of consecutive subcarriers 520 in the frequencydomain. In general, a minimum transmission unit of data is an RB unit,and in an NR system, Nsymb is 14 and NRB is 12 in general.

The structure of wireless time-frequency resources as illustrated inFIG. 5 is applied to a Uu interface. In addition, the structure ofwireless time-frequency resources as illustrated in FIG. 5 may be alsosimilarly applied to a sidelink.

FIG. 6A illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments,FIG. 6B illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments,FIG. 6C illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments, andFIG. 6D illustrates an example of a scenario of sidelink communicationin a wireless communication system according to various embodiments.

FIG. 6A illustrates an in-coverage scenario in which sidelink terminal(UE)s 620 a and 620 b are located in the coverage of a base station 610.The sidelink UEs 620 a and 620 b may receive data and controlinformation through a downlink (DL) from the base station 610, or maytransmit data and control information through an uplink (UL) to the basestation 610. The data and control information may be data and controlinformation for sidelink communication, or may be data and controlinformation for general cellular communication rather than sidelinkcommunication. In addition, in FIG. 6A, the sidelink UEs 620 a and 620 bmay transmit or receive data and control information for sidelinkcommunication through a sidelink.

FIG. 6B illustrates a partial coverage case in which the first UE 620 aamong the sidelink UEs is located in the coverage of the base station610, and the second UE 620 b is located out of the coverage of the basestation 610. The first UE 620 a located in the coverage of the basestation 610 may receive data and control information through a downlinkfrom the base station, or may transmit data and control informationthrough an uplink to the base station. The second UE 620 b located outof the coverage of the base station 610 is unable to receive data andcontrol information through a downlink from the base station, or isunable to transmit data and control information through an uplink to thebase station. The second UE 620 b may transmit or receive data andcontrol information to or from the first UE 620 a for sidelinkcommunication through a sidelink.

FIG. 6C illustrates a case in which sidelink UEs (e.g. the first UE 620a and the second UE 620 b) are located out of the coverage of a basestation. Therefore, the first UE 620 a and the second UE 620 b areunable to receive data and control information through a downlink fromthe base station, or are unable to transmit data and control informationthrough an uplink to the base station. The first UE 620 a and the secondUE 620 b may transmit and receive data and control information forsidelink communication through a sidelink.

FIG. 6D illustrates a case of inter-cell sidelink communicationperformed by the first UE 620 a and the second UE 620 b performingsidelink communication, which are connected to (e.g. an RRC connectionstate) or are camped in (e.g. an RRC disconnection state, i.e. an RRCidle state) different base stations (e.g. a first base station 610 a anda second base station 610 b). The first UE 620 a may be a sidelinktransmission UE, and the second UE 620 b may be a sidelink reception UE.Alternatively, the first UE 620 a may be a sidelink reception UE, andthe second UE 620 b may be a sidelink transmission UE. The first UE 620a may receive a sidelink-dedicated system information block (SIB) fromthe base station 610 a to which the first UE is connected (or in whichthe first UE is camped). The second UE 620 b may receive asidelink-dedicated SIB from the different base station 610 b to whichthe second UE is connected (or in which the second UE is camped).Information of the sidelink-dedicated SIB received by the first UE 620 aand information of the sidelink-dedicated SIB received by the second UE620 b may be different from each other. Therefore, pieces of informationare required to be unified in order to perform sidelink communicationbetween UEs located in different cells.

For convenience of explanation, the examples illustrated in FIGS. 6A to6D have been explained for a sidelink system including two UEs (e.g. thefirst UE 620 a and the second UE 620 b). However, the disclosure is notlimited thereto, and may be also applied to a sidelink system in whichthree or more UEs participate. In addition, uplinks and downlinksbetween the base station 610 and sidelink UEs may be referred to as Uuinterfaces, and sidelinks between sidelink UEs may called PC-5interfaces. In the following description, an uplink or downlink and anUu interface, and a sidelink and PC-5 may be used together.

In the disclosure, a UE may imply a vehicle supportingvehicular-to-vehicular (V2V) communication, a vehicle or a pedestrian'shandset (e.g. smartphone) supporting vehicular-to-pedestrian (V2P)communication, a vehicle supporting vehicular-to-network (V2N)communication, or a vehicle supporting vehicular-to-infrastructure (V21)communication. In addition, in the disclosure, a UE may imply a roadside unit (RSU) equipped with a UE function, an RSU equipped with a basestation function, or an RSU equipped with a part of a base stationfunction and a part of a UE function.

FIG. 7A illustrates an example of a sidelink communication transmissionscheme in a wireless communication system according to variousembodiments, and FIG. 7B illustrates an example of a sidelinkcommunication transmission scheme in a wireless communication systemaccording to various embodiments. FIG. 7A illustrates a unicast scheme,and FIG. 7B illustrates a groupcast scheme.

As illustrated in FIG. 7A, a transmission UE 720 a and a reception UE720 b may perform one-to-one communication with each other. Atransmission scheme as illustrated in FIG. 7A may be called unicastcommunication. As illustrated in FIG. 7B, a transmission UE 720 a or 720d and reception UEs 720 b, 720 c, 720 e, 720 f, and 720 g may performone-to-many communication with each other. A transmission scheme asillustrated in FIG. 7B may be called groupcast or multicast. In FIG. 7B,the first UE 720 a, the second UE 720 b, and the third UE 720 c form onegroup, and performs groupcast communication. The fourth UE 720 d, thefifth UE 720 e, the sixth UE 720 f, and the seventh UE 720 g formanother group, and perform groupcast communication. The UEs may performgroupcast communication in a group to which the UEs belong, and mayperform unicast, groupcast, or broadcast communication with at least oneother UE belonging to a different group. FIG. 7B illustrates two groups,but the disclosure is not limited thereto, and may be applied to moregroups.

Although not illustrated in FIG. 7A or 7B, sidelink UEs may performbroadcast communication. Broadcast communication implies a scheme bywhich all sidelink UEs receive data and control information transmittedthrough a sidelink by a sidelink transmission UE. For example, in FIG.7B, if the first UE 720 a is a transmission UE, the other UEs 720 b, 720c, 720 d, 720 e, 720 f, and 720 g may receive data and controlinformation transmitted by the first UE 720 a.

Sidelink unicast communication, groupcast communication, and broadcastcommunication described above may be supported in an in-coveragescenario, a partial-coverage scenario, or an out-of-coverage scenario.

Unlike an LTE sidelink, a NR sidelink may consider supporting of atransmission type in which a vehicle UE transmits data to only oneparticular UE through unicast, and a transmission type in which avehicle UE transmits data to particular multiple UEs through groupcast.For example, in consideration of a service scenario, for example, aplatooning technology in which two or more vehicles are connected to onenetwork, and move while being bound in a group, unicast and groupcasttechnologies described above may be useful. Specifically, unicastcommunication may be used to allow the leader UE of a group, in whichthe connection is formed by platooning, to control one particular UE,and groupcast communication may be used to control a group includingparticular multiple UEs at the same time.

A V2X system may use the methods as described below for resourceallocation.

(1) Mode 1 Resource Allocation

Scheduled resource allocation corresponds to a method by which a basestation allocates resources used for sidelink transmission toRRC-connected UEs according to a dedicated scheduling scheme. Thescheduled resource allocation method may be effective for interferencemanagement and resource pool management (dynamic allocation and/orsemi-persistent transmission) because a base station can manageresources of a sidelink. If there is data to be transmitted to anotherUE(s), an RRC connection mode UE may transmit information notifying abase station of that there is data to be transmitted to the other UE(s),by using an RRC message or an MAC control element (hereinafter, “CE”).For example, an RRC message transmitted by a UE to a base station may bea sidelink UE information (SidelinkUEInformation) message and a UEassistance information (UEAssistanceInformation) message. An MAC CE maycorrespond to at least one of a scheduling request (SR) includinginformation of the size of data buffered for sidelink communication, ora buffer status report (BSR) MAC CE including at least one of anindicator informing of a BSR for V2X communication.

(2) Mode 2 Resource Allocation

Secondly, UE autonomous resource selection is a method by which asidelink transmission/reception resource pool for V2X is provided to aUE through system information or an RRC message (e.g. an RRCreconfiguration (RRCReconfiguration) message, or a PC5-RRC message), andthe UE selects a resource pool and a resource according to a set rule.The UE autonomous resource selection may correspond to one or multiplemethods among the following resource allocation methods.

-   -   a UE may autonomously select a sidelink resource for        transmission.    -   a UE assists sidelink resource selection for other UEs.    -   a UE is configured with NR configured grant for sidelink        transmission.    -   a UE schedules sidelink transmission of other UEs.    -   a resource selection method of a UE may include zone mapping,        sensing-based resource selection, random selection, etc.

Additionally, even if a UE exists in the coverage of a base station,resource allocation or resource selection based on scheduled resourceallocation or UE autonomous resource selection modes may fail. In thiscase, the UE may perform V2X sidelink communication through apre-configured sidelink transmission/reception resource pool(preconfiguration resource pool).

In addition, if UEs for V2X communication exist out of the coverage of abase station, a UE may perform V2X sidelink communication through apre-configured sidelink transmission/reception resource pool.

An SLRB configuration and an SLRB for transmitting a sidelink flow orpacket may be mapped to an SL logical channel group (LCG), and the SLLCG may be mapped to an SL logical channel. The SLRB configuration andthe SLRB may be distinguished by a combination of a source index, adestination index, a cast type, a QoS flow identifier (QFI)/ProSe flowidentifier or PC5 flow identifier (PFI), or priority, etc.

In a wireless communication system according to various embodiments, asidelink radio bearer may be configured to transmit or receive data,based on a sidelink between UEs. The sidelink radio bearer may be usedfor at least one of sidelink unicast, sidelink groupcast, and sidelinkbroadcast. When packet transmission or reception based on a sidelinkbetween a UE and a UE is performed, the sidelink radio bearer may beconfigured by a bi-directional connection or a uni-directionalconnection. If the sidelink radio bearer is configured by abi-directional connection, each of the UEs may serve as both atransmission UE and a reception UE. If a sidelink radio bearer betweentwo UEs is configured by a bi-directional connection, a part ofconfiguration information used for data transmission or receptionbetween the two UEs may be configured to be the same. For example, anRLC layer mode (RLC mode) may be configured to be an RLC AM or RLC UM.With respect to the sidelink radio bearer configured by thebi-directional connection, it is required that a bi-directional RLC AMis configured identically for the two UEs, or a bi-directional RLC UM isconfigured identically for the two UEs. As another example, if asidelink radio bearer between two UEs is configured by a uni-directionalconnection, a part of configuration information used for datatransmission or reception between the two UEs may be configured to bethe same. With respect to the sidelink radio bearer configured by theuni-directional connection, it is required that a uni-directional RLC AMis configured identically for the two UEs, or a uni-directional RLC UMis configured identically for the two UEs. As another example, if an RLCAM is configured for a sidelink radio bearer configured by abi-directional connection, a sidelink logical channel configured for thetwo UEs is required to be a logical channel corresponding to abi-directional RLC AM. If an RLC UM is configured for a sidelink radiobearer configured by a bi-directional connection, a sidelink logicalchannel configured for the two UEs is required to be a logical channelcorresponding to a bi-directional RLC UM. As another example, if an RLCAM is configured for a sidelink radio bearer configured by auni-directional connection, a sidelink logical channel configured forthe two UEs is required to be a logical channel corresponding to auni-directional RLC AM. If an RLC UM is configured for a sidelink radiobearer configured by a uni-directional connection, a sidelink logicalchannel configured for the two UEs is required to be a logical channelcorresponding to a uni-directional RLC UM. Transmission parameterconfiguration information configured for each of the UEs and/ortransmission/reception parameter configuration information required tobe synchronized between the two UEs may be configured by information (atleast one of information obtained from an RRC-dedicated message,information obtained from an SIB message, and information from apreconfiguration) obtained from a system. Reception parameterconfiguration information configured for each of the UEs may be randomlyconfigured by a corresponding UE. Therefore, if the UEs obtain, from asystem, configuration information of a sidelink radio bearer configuredby a bi-directional connection, a method by which the UEs can obtain thesame configuration information is required. If the UEs obtain, from asystem, configuration information of a sidelink radio bearer configuredby a uni-directional connection, a method by which the UEs can obtainthe same configuration information is required. This is because: the twoUEs may obtain configuration information from different base stations,respectively; one UE may obtain configuration information from anRRC-dedicated message of a base station and the other UE may obtainconfiguration information from an SIB; or one UE may obtainconfiguration information from an RRC-dedicated message/SIB of a basestation and the other UE may obtain configuration information from apreconfiguration.

In a wireless communication system according to various embodiments, NWcoordination may be applied as a method for configuring the sameconfiguration information on a bi-directional or uni-directionalsidelink radio bearer between UEs. An NW coordination method may beapplied to at least one of a system using the same PLMN, a system of thesame service provider, a system of a region to which the same regulationis applied, and the same NW. In the NW coordination method, the samesidelink radio bearer configuration information is required to be usedfor the same ProSe QoS indicator (PQI) in at least one of the same PLMNor the same service provider system, the same regulation system, and thesame NW. In another embodiment, the same sidelink radio bearerconfiguration information is required to be used for at least one of thesame destination ID, the same PC5 flow ID, or the same unicast ID,instead of a PQI. Two UEs performing sidelink-based communication mayexchange at least one of PLMN information, service provider information,regulation information, or NW information in order to determineinformation indicating that the UEs belong to a network using the samesidelink radio bearer configuration information, according to NWcoordination. If it is determined that the two UEs do not belong to thesame NW, the two UEs may perform a configuration coordination operationto have the same configuration information on a bi-directional oruni-directional sidelink radio bearer.

Use information of a bi-directional or uni-directional sidelink radiobearer between two UEs deciding to perform direct communication may beexchanged in a PC5-S signaling setup procedure used for configuring asidelink unicast connection between the two UEs. In another embodiment,use information of a bi-directional or uni-directional sidelink radiobearer between two UEs may be exchanged in a PC5 RRC connectionprocedure used for a sidelink unicast connection between the two UEs. Ifa bi-directional or uni-directional sidelink radio bearer is determinedto be used, based on the information exchanged between the two UEs,whether there is a need of an SLRB configuration coordination operationin a procedure of configuring an SLRB configuration for a sidelinkunicast connection between the two UEs may be determined based on atleast one of PLMN information, service provider information, regulationinformation, or NW information.

FIG. 8A is a signal flow diagram between UEs using a NW coordinationmethod according to various embodiments, and FIG. 8B is a signal flowdiagram between UEs using a NW coordination method according to variousembodiments. FIG. 8A illustrates an embodiment in which, while two UEsperform a PC5-S signaling setup procedure to configure a PC5 unicastconnection, the two UEs exchange NW coordination information, and FIG.8B illustrates an embodiment in which, while two UEs performs a PC5-RRCconfiguration procedure to configure a PC5 unicast connection, the twoUEs exchange NW coordination information.

Referring to FIG. 8A, a UE1 800 and UE2 830 may perform a PC5 signalingprocedure for configuring a sidelink-based unicast connection, inoperation 801. Information exchanged between the two UEs 800 and 830 inthe PC5 signaling procedure may include at least one or a combination ofa PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. In the PC5 signaling procedure,the two UEs 800 and 830 may exchange bi-directional bearer indicationinformation or uni-directional bearer indication information. In the PC5signaling procedure, the two UEs 800 and 830 may exchange NWcoordination information. The NW coordination information may include atleast one or a combination of a PLMN ID, a service provider identifier,a regulation identifier, and an NW identifier.

The UE 830 having received the NW coordination information may determinewhether to apply an SLRB configuration coordination function, inoperation 803. In the embodiment illustrated in FIG. 8A, the UE2 830determines whether to apply the SLRB configuration coordinationfunction. However, the UE1 800 may also determine whether to apply theSLRB configuration coordination function. The determination on whetherto apply the SLRB configuration coordination function corresponds to anoperation of determining whether the UE1 800 and the UE2 830 belong tothe same NW or different NWs, based on the NW coordination information.If it is determined according to a determination performed in operation803, that the application of the SLRB configuration coordinationfunction is necessary, the UE1 800 and the UE2 830 may perform anoperation for applying the SLRB configuration coordination function, inoperation 805. Alternatively, if it is determined according to adetermination performed in operation 803, that the application of theSLRB configuration coordination function is not necessary, the UE1 800and the UE2 830 may perform an operation corresponding to non-applyingof the SLRB configuration coordination function, in operation 805. In acase of non-applying of the SLRB configuration coordination function,the two UEs 800 and 830 may perform a PC5-RRC connection setup procedure(at least one of a UE capability negotiation procedure and an ASconfiguration procedure). According to a result of a determinationperformed in operation 803, the UE1 800 and the UE2 830 may exchangeinformation indicating applying or non-applying the SLRB configurationcoordination function. The SLRB configuration coordination functionwhich can be performed by the UE1 800 and the UE2 830 in operation 805may include at least one or a combination of methods, as illustrated inFIGS. 9 to 20 , of: determining and deciding by UE itself; usingcoordination of a base station; using a designated UE; and processing asan AS configuration failure.

Referring to FIG. 8B, a UE1 850 and UE2 880 may perform a PC5 signalingprocedure for configuring a sidelink-based unicast connection, inoperation 851. Information exchanged between the two UEs 850 and 880 inthe PC5 signaling procedure may include at least one or a combination ofa PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 850 and the UE2 880having performed the PC5-S signaling setup procedure may perform asidelink UE capability information exchange procedure in a PC5 RRCconnection procedure, in operation 853. The UE1 850 and the UE2 880 mayperform an AS configuration procedure in the PC5 RRC connectionprocedure, in operation 855. The AS configuration procedure maycorrespond to a procedure of configuring configuration information of asidelink radio bearer between the two UEs 850 and 880. Informationexchanged in the AS configuration procedure may include at least one ora combination of a PC5 flow ID, a destination ID, a source ID, a PQI,QoS characteristics, and a PC5 SLRB configuration. In the ASconfiguration procedure, the two UEs 850 and 880 may exchangebi-directional bearer indication information or uni-directional bearerindication information. In the AS configuration procedure, the two UEsmay exchange NW coordination information. The NW coordinationinformation may include at least one or a combination of a PLMN ID, aservice provider identifier, a regulation identifier, and an NWidentifier.

The UE 880 having received the NW coordination information may determinewhether to apply an SLRB configuration coordination function, inoperation 857. In the embodiment illustrated in FIG. 8B, the UE2 880determines whether to apply the SLRB configuration coordinationfunction. However, the UE1 850 may also determine whether to apply theSLRB configuration coordination function. The determination on whetherto apply the SLRB configuration coordination function corresponds to anoperation of determining whether the UE1 850 and the UE2 880 belong tothe same NW or different NWs, based on the NW coordination information.

If it is determined according to a determination performed in operation857, that the application of the SLRB configuration coordinationfunction is necessary, the UE1 850 and the UE2 880 may perform anoperation for applying the SLRB configuration coordination function, inoperation 859. Alternatively, if it is determined according to adetermination performed in operation 857, that the application of theSLRB configuration coordination function is not necessary, the UE1 850and the UE2 880 may perform an operation corresponding to non-applyingof the SLRB configuration coordination function, in operation 859. In acase of non-applying of the SLRB configuration coordination function,the two UEs 850 and 880 may perform a PC5-RRC connection setup procedure(at least one of a UE capability negotiation procedure and an ASconfiguration procedure). According to a result of a determinationperformed in operation 857, the UE1 850 and the UE2 880 may exchangeinformation indicating applying or non-applying the SLRB configurationcoordination function. The SLRB configuration coordination functionwhich can be performed by the UE1 850 and the UE2 880 in operation 859may include at least one or a combination of methods, as illustrated inFIGS. 9 to 20 , of: determining and deciding by UE itself; usingcoordination of a base station; using a designated UE; and processing asan AS configuration failure.

According to various embodiments, a method for coordinatingconfiguration information of a sidelink radio bearer between UEsperforming sidelink-based direct communication may include at least oneor a combination of the following methods.

(1) Determination and decision made by a UE itself: Radio bearerconfiguration information may be coordinated through signaling exchangebetween two UEs. The two UEs may correspond to an initiating UE or apeer UE which performs a PC5-S signaling procedure for configuring asidelink connection. In various embodiments, a UE transmitting the firstmessage of a PC5-S signaling procedure will be called an initiating UE,and a UE receiving the first message of the PC5-S signaling procedureand transmitting a response (acceptance of connection configuration)message to the first message will be called a peer UE.

(2) Decision made through coordination by a base station: Two UEs maycoordinate radio bearer configuration information by reporting the radiobearer configuration information to a base station accessed by the twoUEs, and obtaining identification and adjustment information relating tothe radio bearer configuration information from the base station.

(3) Designation of a UE deciding a sidelink radio bearer (SLRB)configuration, and determination and decision made by the designated UE:For example, a designated UE may correspond to a UE that obtains andprovides a bi-directional SLRB configuration and/or a uni-directionalSLRB configuration. Another UE may receive, from the designated UE, abi-directional SLRB configuration and/or a uni-directional SLRBconfiguration and use the received configuration. For example, thedesignated UE may correspond to a UE that determines a match or mismatchbetween bi-directional SLRB configurations and/or uni-directional SLRBconfigurations obtained by the UEs, and notifies the other UE of thedetermined match or mismatch. If SLRB configuration mismatch informationis received from the designated UE, the other UE may perform abi-directional SLRB configuration and/or uni-directional SLRBconfiguration coordination procedure together with the designated UE.For example, the designated UE may correspond to a UE that, when the UEdetermines whether bi-directional SLRB configurations and/oruni-directional SLRB configurations obtained by the UEs mismatch eachother, performs SLRB configuration coordination and fixes SLRBconfigurations to be used by the UEs. The other UE may receive, from thedesignated UE, a final bi-directional SLRB configuration and/oruni-directional SLRB configuration and use the received configuration.

The designated UE may: decide a bi-directional SLRB configuration and/oruni-directional SLRB configuration, based on sidelink radio bearerconfiguration information obtained by the designated UE itself (obtainedthrough at least one of a dedicated RRC message of an NW, an SIB, and apreconfiguration); determine coordination with an SLRB configurationreceived from the other UE, based on the obtained SLRB configuration,and decide a bi-directional SLRB configuration and/or uni-directionalSLRB configuration; report SLRB configuration information received fromthe other UE to a base station of the designated UE, and decide abi-directional SLRB configuration and/or uni-directional SLRBconfiguration, based on information identified by the base station; orreport SLRB configuration information received from the other UE to thebase station of the designated UE, and obtain a final bi-directionalSLRB configuration and/or uni-directional SLRB configuration from thebase station. If a final bi-directional SLRB configuration and/oruni-directional SLRB configuration is obtained, the designated UE maytransfer the information to the other UE.

An embodiment of a method for selecting a designated UE may include atleast one of methods of: selecting an initiating UE as a designated UE;selecting a peer UE as a designated UE; or selecting an RRC Connected UEas a designated UE. According to various embodiments, a method ofselecting an SLRB configuration deciding UE will be described withreference to FIG. 9 .

(4) Determination as configuration information acquisition failure (ASconfiguration failure): If it is determined to be difficult tocoordinate bi-directional SLRB configurations and/or uni-directionalSLRB configurations of two UEs, and/or it is determined thatbi-directional SLRB configuration and/or uni-directional SLRBconfiguration information obtained by the two UEs mismatch, an ASconfiguration failure may be determined, and the UEs may perform an ASconfiguration failure procedure. An AS configuration failure processingmethod may be used while being combined with method (1), (2), or (3), ormay be used alone. A UE which determines an AS configuration failurecaused by a collision between bi-directional SLRB configurations and/oruni-directional SLRB configurations may transmit an AS configurationfailure message to an opponent UE, and the AS configuration failuremessage may include at least one of AS configuration failure indicationinformation and collided SLRB configuration parameter information.

FIG. 9 illustrates a method of selecting a UE deciding an SLRBconfiguration according to various embodiments.

A UE1 900 may transmit a PC5-S signaling message A to start a sidelinkunicast connection setup procedure, in operation 901. The message A mayinclude at least one or a combination of a PC5 flow ID, a destinationID, a source ID, a PQI, QoS characteristics, and a PC5 unicast ID. Themessage A may include information indicating a bi-directional connectionand/or uni-directional connection. The message A may include informationindicating an SLRB-configuration designated UE for a bi-directionalconnection and/or uni-directional connection. For example, theinformation indicating the designated UE may indicate that the UE1 900is to serve as the designated UE. For example, the informationindicating the designated UE may indicate that a peer UE is to serve asthe designated UE. For example, the information indicating thedesignated UE may indicate that if a peer UE is an RRC Connected UE, thepeer UE is to serve as the designated UE.

If a UE2 930 receives the message A and accepts sidelink connectionsetup requested by the message A, the UE2 may transmit a PC5-S signalingmessage B to the UE1 900 in operation 903, and may serve as a peer UE.If the UE2 930 receives the message A and does not accept the sidelinkconnection setup requested by the message A, the UE2 may not transmit aresponse message to the UE1 900, or may transmit a connection setuprejection message to the UE1. If the sidelink connection setup requestedby the message A is accepted, the message B may include at least one ora combination of a PC5 flow ID, a destination ID, a source ID, a PQI,QoS characteristics, and a PC5 unicast ID, which corresponds to themessage A. The message B may include bi-directional connection and/oruni-directional connection response information. The message B mayinclude designated UE response information responding to theSLRB-configuration designated UE for a bi-directional connection and/oruni-directional connection. For example, the designated UE responseinformation may include an ack that the UE1 900 is to serve as thedesignated UE. For example, the designated UE response information mayinclude information of responding that the UE2 930 is to serve as thedesignated UE. For example, the designated UE response information mayinclude information of responding that UE2 930 is unable to serve as thedesignated UE. If the UE2 930 responds that the UE2 is unable to serveas the designated UE, the UE1 900 may serve as the designated UE.

If a response message of operation 903 is received, the UE1 900 mayidentify information relating to a bi-directional connection and/oruni-directional connection, and designated UE information (operation905). If the response message of operation 903 is transmitted, the UE2930 may identify the information relating to a bi-directional connectionand/or uni-directional connection, and the designated UE information(operation 907). The UE1 900 and the UE2 930 may perform an RRCconnection setup procedure for a sidelink bi-directional radio bearerconnection and/or sidelink uni-directional radio bearer connection(operation 909). The sidelink RRC connection setup procedure may includeat least one of a UE capability procedure of exchanging sidelink UEcapability information, and an AS configuration procedure of exchangingsidelink radio bearer configuration information. In the AS configurationprocedure, the designated UE may: obtain and decide a bi-directionalSLRB configuration and/or uni-directional SLRB configuration; and/ordetermine whether there is a need to coordinate a bi-directional SLRBconfiguration and/or uni-directional SLRB configuration, and decide abi-directional SLRB configuration and/or uni-directional SLRBconfiguration which is to be used by each of the two UEs.

FIG. 10A illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments, FIG. 10B illustrates a method of SLRB configurationcoordination determined and decided by a terminal itself according tovarious embodiments, FIG. 11 illustrates a method of SLRB configurationcoordination determined and decided by a terminal itself according tovarious embodiments, and FIG. 12 illustrates a method of SLRBconfiguration coordination determined and decided by a terminal itselfaccording to various embodiments.

The UE may correspond to an initiating UE and/or a peer UE that is toperform data transmission or reception through a sidelink unicastconnection, and may decide a bi-directional SLRB configuration oruni-directional SLRB configuration which UEs is to use in the sidelinkunicast connection. A UE transmitting the first message of PC5-Ssignaling to start a sidelink unicast connection setup procedure iscalled an initiating UE. A peer UE indicates a UE receiving the firstmessage of PC5-S signaling, starting the sidelink unicast connectionsetup procedure, and transmitting a response (acceptance of connectionsetup) message corresponding to the message. In an embodiment, theinitiating UE may include a bi-directional SLRB configuration oruni-directional SLRB configuration in an AS configuration message, andtransfer the AS configuration message to the peer UE. In an embodiment,the SLRB configuration may include at least one or a combination of anRLC mode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. In an embodiment, the peer UE may waituntil an AS configuration is received from the initiating UE, and if anAS configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration is received from the initiating UE,the peer UE may perform data transmission or reception based on asidelink according to the SLRB configuration. In an embodiment, during await time interval taken to receive an AS configuration including abi-directional SLRB configuration or uni-directional SLRB configurationfrom the initiating UE, the peer UE may operate a timer, and if the ASconfiguration is received, the peer UE may release the timer. In anembodiment, if the peer UE determines that an AS configuration includinga bi-directional SLRB configuration or uni-directional SLRBconfiguration fails to be received until the timer has expired, the peerUE may obtain a bi-directional SLRB configuration or uni-directionalSLRB configuration, and transfer an AS configuration including thebi-directional SLRB configuration or uni-directional SLRB configurationto the initiating UE. In an embodiment, the peer UE may include, in anAS configuration message including a bi-directional SLRB configurationor uni-directional SLRB configuration, information indicating that thetransmission of the message is an AS configuration transmissionperformed after the expiration of the timer, and may transmit themessage to the initiating UE. In an embodiment, if an AS configurationincluding a bi-directional SLRB configuration or uni-directional SLRBconfiguration is received from the peer UE, the initiating UE maydetermine to follow the bi-directional SLRB configuration oruni-directional SLRB configuration obtained from the peer UE. In anembodiment, if an AS configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration is received from thepeer UE, the initiating UE may perform a configuration informationcoordination procedure for configuration information required to becoordinated, together with the peer UE. In an embodiment, if theinitiating UE receives an AS configuration including a bi-directionalSLRB configuration or uni-directional SLRB configuration from the peerUE, and determines that the SLRB configuration is unable to be applied,the initiating UE may transmit a message indicating an AS configurationfailure to the peer UE.

In an embodiment, if the peer UE determines that an AS configurationincluding a bi-directional SLRB configuration or uni-directional SLRBconfiguration fails to be received until the timer has expired, the peerUE may determine an AS configuration failure, and transfer the ASconfiguration failure to the initiating UE. In an embodiment, if amessage indicating an AS configuration failure is received from the peerUE, the initiating UE may determine not to proceed with the ASconfiguration setup procedure any longer. In an embodiment, if an ASconfiguration complete message fails to be received from the peer UE,the initiating UE may determine not to proceed with the AS configurationsetup procedure any longer. The initiating UE may operate a separatetimer (by starting the timer when an AS configuration message istransmitted, and releasing the timer when an AS configuration completemessage is received) to determine whether an AS configuration completemessage is received. In an embodiment, in a case where the initiating UEoperates a separate timer until an AS configuration complete message isreceived as a response to an AS configuration message, if it isdetermined that an AS configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration is received from thepeer UE, the initiating UE may release the separate timer. In anembodiment, if the peer UE transmits an AS configuration messageincluding a bi-directional SLRB configuration or uni-directional SLRBconfiguration to the initiating UE, the peer UE may operate a separatetimer (by starting the timer when an AS configuration message istransmitted, and releasing the timer when an AS configuration completemessage is received). If the peer UE fails to receive an ASconfiguration complete message from the initiating UE before theexpiration of the separate timer, the peer UE may determine not toproceed with the AS configuration setup procedure any longer. In anembodiment, if the peer UE transmits an AS configuration messageincluding a bi-directional SLRB configuration or uni-directional SLRBconfiguration, and then receives a message notifying of an ASconfiguration failure from the initiating UE, the peer UE may determinenot to proceed with the AS configuration setup procedure any longer.

A timer operation performed by a UE for configuring a bi-directionalSLRB configuration or uni-directional SLRB configuration may employ atleast one of the following methods. The timer may be operated for acorresponding sidelink connection requiring the configuring of abi-directional SLRB configuration or uni-directional SLRB configuration.The corresponding sidelink connection may be distinguished by at leastone or a combination of a destination ID, a source ID, a PC5 flow ID, aPC5 unicast ID, and a PQI. In an embodiment, a timer operated by thepeer UE until a bi-directional SLRB configuration or uni-directionalSLRB configuration is received may start after a PC5-S unicastconnection setup procedure. In an embodiment, a timer operated by thepeer UE until a bi-directional SLRB configuration or uni-directionalSLRB configuration is received may start after UE capability informationof the peer UE is transmitted to the initiating UE. In an embodiment, atimer operated by the peer UE until a bi-directional SLRB configurationor uni-directional SLRB configuration is received may start after UEcapability information is received from the initiating UE. The timer maybe released when an AS configuration message including a bi-directionalSLRB configuration or uni-directional SLRB configuration is receivedfrom the initiating UE.

In a case where the initiating UE or the peer UE receives an ASconfiguration message including a bi-directional SLRB configuration oruni-directional SLRB configuration, and transmits a message indicatingan AS configuration failure in response to the message, the ASconfiguration complete message described above may include at least oneof an AS configuration failure indicator, and/or indication information(the information is at least one of an RLC mode, a bi-directional RLC, auni-directional RLC, and logical channel information mapped to an RLCmode) relating to configuration information causing an AS configurationfailure.

Referring to FIG. 10A, a UE1 1000 and UE2 1030 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1001. Information exchanged between the two UEs 1000 and1030 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1000 and the UE2 1030 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1003.

The UE1 1000 may obtain an SLRB configuration including a bi-directionalSLRB configuration or uni-directional SLRB configuration, in operation1005. According to an embodiment, the SLRB configuration may include atleast one or a combination of an RLC mode, a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and an operational parameter corresponding to the RLC mode. The SLRBconfiguration may be obtained through at least one of a dedicated RRCmessage, an SIB, and a preconfiguration. In operation 1007, the UE1 1000may transmit an AS configuration message to the UE2 1030 to perform anAS configuration procedure in the PC5 RRC connection procedure togetherwith the UE2 1030. The AS configuration message may include at least oneor a combination of a PC5 flow ID, a destination ID, a source ID, a PQI,QoS characteristics, a PC5 SLRB configuration, and a PC5 SLRB ID.

When the AS configuration message is received, the UE2 1030 may obtainthe SLRB configuration including the bi-directional SLRB configurationor uni-directional SLRB configuration, in operation 1009. The UE2 1030may transmit an AS configuration complete message to the UE1 1000 as aresponse to the AS configuration message, in operation 1011. The ASconfiguration complete message may include at least one or a combinationof information corresponding to the AS configuration message, a PC5 flowID, a destination ID, a source ID, a PQI, a PC5 SLRB configuration, anda PC5 SLRB ID. In operation 1013, the UE1 1000 and the UE2 1030 mayperform sidelink data transmission or reception by applying an ASconfiguration including the bi-directional SLRB configuration oruni-directional SLRB configuration.

Referring to FIG. 10B, a UE1 1050 and UE2 1080 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1051. Information exchanged between the two UEs 1050 and1080 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE2 1080 may start a timerfor configuring an AS configuration, in operation 1053. The UE1 1050 andthe UE2 1080 may perform a sidelink UE capability information exchangeprocedure in a PC5 RRC connection procedure, in operation 1055.

The UE1 1050 may obtain an SLRB configuration including a bi-directionalSLRB configuration or uni-directional SLRB configuration, in operation1057. For example, the SLRB configuration may include at least one or acombination of an RLC mode, a bi-directional RLC, a uni-directional RLC,a logical channel corresponding to the RLC mode, and an operationalparameter corresponding to the RLC mode. The SLRB configuration may beobtained through at least one of a dedicated RRC message, an SIB, and apreconfiguration. In operation 1059, the UE1 1050 may transmit an ASconfiguration message to the UE2 1080 to perform an AS configurationprocedure in the PC5 RRC connection procedure together with the UE21080. The AS configuration message may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, a PC5 SLRB configuration, and a PC5 SLRB ID.

If an AS configuration message including a bi-directional SLRBconfiguration or uni-directional SLRB configuration is received, the UE21080 may release the timer in operation 1061. The UE2 1080 may obtainthe bi-directional SLRB configuration or uni-directional SLRBconfiguration included in the AS configuration message, in operation1063. The UE2 1080 may transmit an AS configuration complete message tothe UE1 1050 as a response to the AS configuration message, in operation1065. The AS configuration complete message may include at least one ora combination of information corresponding to the AS configurationmessage, a PC5 flow ID, a destination ID, a source ID, a PQI, a PC5 SLRBconfiguration, and a PC5 SLRB ID. In operation 1067, the UE1 1050 andthe UE2 1080 may perform sidelink data transmission or reception byapplying an AS configuration including the bi-directional SLRBconfiguration or uni-directional SLRB configuration.

Referring to FIG. 11 , a UE1 1100 and UE2 1150 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1101. Information exchanged between the two UEs 1100 and1150 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE2 1150 may start a timerfor configuring an AS configuration, in operation 1103. The UE1 1105 andthe UE2 1107 may perform a sidelink UE capability information exchangeprocedure in a PC5 RRC connection procedure, in operation 1105.

The UE2 1150 may determine the expiration of the timer in operation1107, and may determine that an AS configuration message including abi-directional SLRB configuration or uni-directional SLRB configurationis not received from the UE1 1100. The UE2 1150 may obtain an SLRBconfiguration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1109. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

The UE2 1150 may transmit an AS configuration message including theobtained bi-directional SLRB configuration or uni-directional SLRBconfiguration to the UE1 1100, in operation 1111. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID. According to an embodiment, the ASconfiguration message may include information indicating that thetransmission of the message is an AS configuration transmissionperformed after the expiration of the timer.

When the AS configuration message is received, the UE1 1100 may obtainthe SLRB configuration including the bi-directional SLRB configurationor uni-directional SLRB configuration, in operation 1113. The UE1 1100may transmit an AS configuration complete message to the UE2 1150 as aresponse to the AS configuration message, in operation 1115. The ASconfiguration complete message may include at least one or a combinationof information corresponding to the AS configuration message, a PC5 flowID, a destination ID, a source ID, a PQI, a PC5 SLRB configuration, anda PC5 SLRB ID. In operation 1117, the UE1 1100 and the UE2 1150 mayperform sidelink data transmission or reception by applying an ASconfiguration including the bi-directional SLRB configuration oruni-directional SLRB configuration.

Referring to FIG. 12 , a UE1 1200 and UE2 1250 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1201. Information exchanged between the two UEs 1200 and1250 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE2 1250 may start a timerfor configuring an AS configuration, in operation 1203. The UE1 1200 andthe UE2 1250 may perform a sidelink UE capability information exchangeprocedure in a PC5 RRC connection procedure, in operation 1205.

The UE1 1200 may obtain an SLRB configuration including a bi-directionalSLRB configuration or uni-directional SLRB configuration, in operation1207. For example, the SLRB configuration may include at least one or acombination of an RLC mode, a bi-directional RLC, a uni-directional RLC,a logical channel corresponding to the RLC mode, and an operationalparameter corresponding to the RLC mode. The SLRB configuration may beobtained through at least one of a dedicated RRC message, an SIB, and apreconfiguration. In operation 1209, the UE1 1200 may transmit an ASconfiguration message to the UE2 1250 to perform an AS configurationprocedure in the PC5 RRC connection procedure together with the UE21250. The AS configuration message may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, a PC5 SLRB configuration, and a PC5 SLRB ID.

The UE2 1250 may determine the expiration of the timer in operation1211, and may determine that an AS configuration message including abi-directional SLRB configuration or uni-directional SLRB configurationis not received from the UE1 1210. The UE2 1250 may obtain an SLRBconfiguration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1213. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

The UE2 1250 may transmit an AS configuration message including theobtained bi-directional SLRB configuration or uni-directional SLRBconfiguration to the UE1 1200, in operation 1215. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID. Information including at least one ora combination of the PC5 flow ID, the destination ID, the source ID, thePQI, and the QoS characteristics may be configured to be the same as theinformation exchanged between the UE1 1200 and the UE2 1250 in operation1201. According to an embodiment, the UE2 1250 may include, in the ASconfiguration message transmitted in operation 1215, informationindicating that the transmission of the message is an AS configurationtransmission after the expiration of a bi-directional SLRB configurationsetup timer or the expiration of a uni-directional SLRB configurationsetup timer.

If, after the AS configuration message including the bi-directional SLRBconfiguration or the uni-directional SLRB configuration is transmittedin operation 1215, the AS configuration message transmitted by the UE11200 is received (operation 1209), the UE2 1250 may ignore the ASconfiguration message transmitted by the UE1 1200. If, after the ASconfiguration message including the bi-directional SLRB configuration orthe uni-directional SLRB configuration is transmitted in operation 1209,a bi-directional SLRB configuration or uni-directional SLRBconfiguration related to the same sidelink connection is received fromthe UE2 1250, the UE1 1200 may determine to ignore the SLRBconfiguration transmitted in operation 1209, and may obtain thebi-directional SLRB configuration or uni-directional SLRB configurationreceived from the UE2 1250 in operation 1215, in operation 1217.

The UE1 1200 may transmit an AS configuration complete message to theUE2 1250 as a response to the AS configuration message of operation1215, in operation 1219. The AS configuration complete message mayinclude at least one or a combination of information corresponding tothe AS configuration message of the operation 1215, a PC5 flow ID, adestination ID, a source ID, a PQI, a PC5 SLRB configuration, and a PC5SLRB ID. In operation 1221, the UE1 1200 and the UE2 1250 may performsidelink data transmission or reception by applying an AS configurationincluding the bi-directional SLRB configuration or uni-directional SLRBconfiguration.

In the embodiments illustrated in FIGS. 10, 11, and 12 , if aftertransmitting an AS configuration message, the UE1 fails to receive an ASconfiguration complete message from the UE2, or the UE1 receives an ASconfiguration complete message indicating an AS configuration failurefrom the UE2, the UE1 and the UE2 may not proceed with the ASconfiguration setup procedure any longer. In the embodiment illustratedin FIG. 12 , if after transmitting an AS configuration message, the UE2fails to receive an AS configuration complete message from the UE1, orthe UE2 receives an AS configuration complete message indicating an ASconfiguration failure from the UE1, the UE1 and the UE2 may not proceedwith the AS configuration setup procedure any longer.

FIG. 13 illustrates a method of SLRB configuration coordinationdetermined and decided by a terminal itself according to variousembodiments, FIG. 14 illustrates a method of SLRB configurationcoordination determined and decided by a terminal itself according tovarious embodiments, FIG. 15A illustrates a method of SLRB configurationcoordination determined and decided by a terminal itself according tovarious embodiments, FIG. 15B illustrates a method of SLRB configurationcoordination determined and decided by a terminal itself according tovarious embodiments, and FIG. 15C illustrates a method of SLRBconfiguration coordination determined and decided by a terminal itselfaccording to various embodiments.

The embodiments illustrated in FIGS. 13 to 15 provide a method forobtaining, by an initiating UE and a peer UE configuring a sidelinkunicast connection, respective sidelink configuration information,determining whether there is a collision of bi-directional SLRBconfiguration information or uni-directional SLRB configurationinformation in an AS configuration setup procedure performed between thetwo UEs, and processing a collision/non-collision.

For example, the initiating UE may transfer an SLRB configurationobtained by itself to the peer UE, and the peer UE may determine whetheran SLRB configuration obtained by itself collides with the SLRBconfiguration received from the initiating UE. For example, if it isdetermined that the SLRB configuration received from the initiating UEand the SLRB configuration obtained by the peer UE itself do notcollide, the peer UE may transfer, to the initiating UE, a responsemessage confirming the application of the SLRB configuration. Forexample, if it is determined that the SLRB configuration received fromthe initiating UE and the SLRB configuration obtained by the peer UEitself collide with each other, the peer UE may transmit, to theinitiating UE, a message indicating an AS configuration failure.

For example, if it is determined that the SLRB configuration receivedfrom the initiating UE and the SLRB configuration obtained by the peerUE itself collide with each other, the peer UE may determine to performan SLRB configuration adjustment procedure together with the initiatingUE. For example, the peer UE may transfer an SLRB configurationadjustment message including adjustable parameter information to theinitiating UE. For example, the initiating UE may receive a responsemessage confirming the application of the SLRB configuration obtained bythe initiating UE itself, from the peer UE. For example, the initiatingUE may receive a message indicating an AS configuration failure from thepeer UE. For example, the initiating UE may receive an SLRBconfiguration adjustment message including adjustable parameterinformation to from the peer UE.

For example, when an SLRB configuration adjustment message includingadjustable parameter information is received from the peer UE, theinitiating UE may determine whether the initiating UE can accept anadjustable parameter, and may transmit an SLRB configuration adjustmentresponse message including the acceptance of the parameter to the peerUE. For example, when an SLRB configuration adjustment message includingadjustable parameter information is received from the peer UE, theinitiating UE may determine whether the initiating UE can accept anadjustable parameter, and may transmit an SLRB configuration adjustmentresponse message indicating an AS configuration failure caused by“unable to accept the parameter” to the peer UE.

For example, when an SLRB configuration adjustment message includingadjustable parameter set information is received from the peer UE, theinitiating UE may select a parameter to be applied in an adjustableparameter set, and may transmit an SLRB configuration adjustment messageincluding information of the selected parameter to the peer UE. The peerUE may receive, from the initiating UE, an SLRB configuration adjustmentmessage including information of a parameter to be applied in theadjustable parameter set. For example, if the initiating UE fails toreceive, from the peer UE, a response message related to an ASconfiguration including a bi-directional SLRB configuration obtained bythe initiating UE itself, the initiating UE may determine an ASconfiguration failure.

Referring to FIG. 13 , a UE1 1300 and UE2 1330 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1301. Information exchanged between the two UEs 1300 and1330 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1300 and the UE2 1330 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1303. The UE1 1300 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1305. The UE2 1330 mayobtain an SLRB configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration, in operation 1307.The SLRB configuration may include at least one or a combination of anRLC mode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1309, the UE1 1300 may transmit an AS configuration messageto the UE2 1330 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1330. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

If the AS configuration message is received, the UE2 1330 may determinewhether the SLRB configuration obtained in operation 1307 collides withthe SLRB configuration included in the AS configuration message, inoperation 1311. A target parameter determining whether the SLRBconfigurations collide with each other may include at least one ofconfiguration parameters of RLC mode operations in addition to at leastone or a combination of an RLC mode (RLC AM or RLC UM), a bi-directionalRLC, a uni-directional RLC, and a logical channel corresponding to theRLC mode.

If it is determined that the SLRB configurations do not collide witheach other in operation 1311, the UE 2 1330 may transfer an ASconfiguration complete message to the UE1 1300 as a response to the ASconfiguration message received in operation 1309, in operation 1313. TheAS configuration complete message may include at least one or acombination of information corresponding to the AS configurationmessage, a PC5 flow ID, a destination ID, a source ID, a PQI, a PC5 SLRBconfiguration, and a PC5 SLRB ID. In operation 1315, the UE1 1300 andthe UE2 1330 may perform sidelink data transmission or reception byapplying an AS configuration including the SLRB configuration.

Referring to FIG. 14 , a UE1 1400 and UE2 1430 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1401. Information exchanged between the two UEs 1400 and1430 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1400 and the UE2 1430 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1403.

The UE1 1400 may obtain an SLRB configuration including a bi-directionalSLRB configuration or uni-directional SLRB configuration, in operation1405. The UE2 1430 may obtain an SLRB configuration including abi-directional SLRB configuration or uni-directional SLRB configuration,in operation 1407. For example, the SLRB configuration may include atleast one or a combination of an RLC mode, a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and an operational parameter corresponding to the RLC mode. The SLRBconfiguration may be obtained through at least one of a dedicated RRCmessage, an SIB, and a preconfiguration.

In operation 1409, the UE1 1400 may transmit an AS configuration messageto the UE2 1430 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1430. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

If the AS configuration message is received, the UE2 1430 may determinewhether the SLRB configuration obtained in operation 1407 collides withthe SLRB configuration included in the AS configuration message, inoperation 1411. A target parameter determining whether the SLRBconfigurations collide with each other may include at least one ofconfiguration parameters of RLC mode operations in addition to at leastone or a combination of an RLC mode (RLC AM or RLC UM), a bi-directionalRLC, a uni-directional RLC, and a logical channel corresponding to theRLC mode. If it is determined that the SLRB configurations collide witheach other in operation 1411, the UE 2 1430 may determine an ASconfiguration failure, and transfer an AS configuration complete messageto the UE1 1400 as a response to the AS configuration message receivedin operation 1409, in operation 1413. The AS configuration completemessage may include at least one or a combination of informationcorresponding to the AS configuration message, a PC5 flow ID, adestination ID, a source ID, a PQI, a PC5 SLRB ID, and failureindication information. For example, the UE2 1430 may include, in the ASconfiguration complete message, information of a parameter causing thecollision between the SLRB configurations.

If the AS configuration complete message indicating an AS configurationfailure is received from the UE2 1430, the UE1 1400 may determine an ASconfiguration failure and stop the AS configuration procedure (operation1413). If the AS configuration complete message includes informationindicating that the cause of an AS configuration failure corresponds toan SLRB configuration parameter, the UE1 1400 may determine that therehas been a collision between the SLRB configurations (operation 1415).In an embodiment, the UE1 1400 may report, to an NW, that an ASconfiguration failure has occurred due to a collision between the SLRBconfigurations. Information reported to the NW may include at least oneor a combination of a PQI, PC5 QoS characteristics, a PC5 flow ID, and aconfiguration parameter by which the collision has occurred, such as, anRLC mode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode.

Referring to FIG. 15A, a UE1 1500 and UE2 1530 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1501. Information exchanged between the two UEs 1500 and1530 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1500 and the UE2 1530 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1503. The UE1 1500 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1505. The UE2 1530 mayobtain an SLRB configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration, in operation 1507.For example, the SLRB configuration may include at least one or acombination of an RLC mode, a bi-directional RLC, a uni-directional RLC,a logical channel corresponding to the RLC mode, and an RLC operationalparameter corresponding to the RLC mode. The SLRB configuration may beobtained through at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1509, the UE1 1500 may transmit an AS configuration messageto the UE2 1530 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1530. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

If the AS configuration message is received, the UE2 1530 may determinewhether the SLRB configuration obtained in operation 1507 collides withthe SLRB configuration included in the AS configuration message, inoperation 1511. A target parameter determining whether the SLRBconfigurations collide with each other may include at least one or acombination of an RLC mode (RLC AM or RLC UM), a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and a configuration parameter required for the operation of the RLCmode.

If it is determined that the SLRB configurations collide with each otherin operation 1511, the UE2 1530 may identify information of aconfiguration parameter required to be adjusted due to a mismatch. TheUE2 1530 may transmit an AS configuration message including theinformation of the configuration parameter required to be adjusted, inoperation 1513. The AS configuration message of operation 1513 mayinclude information of a configuration parameter required to beadjusted, corresponding to the at least one or combination of the PC5flow ID, the destination ID, the source ID, the PQI, the QoScharacteristics, the PC5 SLRB configuration, and the PC5 SLRB ID, whichis received in operation 1509. The information of the configurationparameter required to be adjusted may include at least one of anadjustable RLC mode (RLC AM or RLC UM), a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and a configuration parameter required for the operation of the RLCmode.

The UE1 1500 having received the AS configuration message of operation1513 may determine that the SLRB configurations are required to beadjusted, in operation 1515. The UE1 1500 may perform a parameteradjustment of the configuration parameter determined to be required tobe adjusted, and may transmit an AS configuration message includinginformation relating to the parameter adjustment to the UE2 1530, inoperation 1517. The AS configuration message of operation 1517 mayinclude information of an adjusted configuration parameter,corresponding to the at least one or combination of the PC5 flow ID, thedestination ID, the source ID, the PQI, the QoS characteristics, the PC5SLRB configuration, and the PC5 SLRB ID, which is received in operation1513. The information of the adjusted configuration parameter requiredto be adjusted may include at least one of an RLC mode (RLC AM or RLCUM), a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and a configuration parameter requiredfor the operation of the RLC mode.

If the AS configuration message of operation 1517 is received, the UE21530 may transmit an AS configuration complete message as a response tothe above message (operation 1519). The AS configuration completemessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID. In operation 1521, the UE1 1500 andthe UE2 1530 may perform sidelink data transmission or reception byapplying an AS configuration including the SLRB configuration.

Referring to FIG. 15B, a UE1 1540 and UE2 1560 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1541. Information exchanged between the two UEs 1540 and4560 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1540 and the UE2 1560 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1543. The UE1 1540 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1545. The UE2 1560 mayobtain an SLRB configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration, in operation 1547.For example, the SLRB configuration may include at least one or acombination of an RLC mode, a bi-directional RLC, a uni-directional RLC,a logical channel corresponding to the RLC mode, and an operationalparameter corresponding to the RLC mode. The SLRB configuration may beobtained through at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1549, the UE1 1540 may transmit an AS configuration messageto the UE2 1560 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1560. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

If the AS configuration message is received, the UE2 1560 may determinewhether the SLRB configuration obtained in operation 1547 collides withthe SLRB configuration included in the AS configuration message, inoperation 1551. A target parameter determining whether the SLRBconfigurations collide with each other may include at least one or acombination of an RLC mode (RLC AM or RLC UM), a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and a configuration parameter required for operation of the RLC mode. Ifit is determined that the SLRB configurations collide with each other inoperation 1551, the UE2 1560 may identify information of a configurationparameter required to be adjusted due to a mismatch.

The UE2 1560 may transmit an AS configuration message including theinformation of the configuration parameter required to be adjusted, inoperation 1553. The AS configuration message of operation 1553 mayinclude information of a configuration parameter required to beadjusted, corresponding to the at least one or combination of the PC5flow ID, the destination ID, the source ID, the PQI, the QoScharacteristics, the PC5 SLRB configuration, and the PC5 SLRB ID, whichis received in operation 1549. The information of the configurationparameter required to be adjusted may include at least one of anadjustable RLC mode (RLC AM or RLC UM), a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and a configuration parameter required for the operation of the RLCmode.

The UE1 1540 having received the AS configuration message of operation1553 may determine whether the SLRB configuration is adjustable, basedon the information of the configuration parameter of the ASconfiguration received in operation 1553, in operation 1555. If it isdetermined that the adjustment of the configuration parameter ispossible, the UE1 1540 may transmit an AS configuration complete messageto the UE2 1560, in operation 1557. The AS configuration completemessage may include at least one or a combination of the PC5 flow ID,the destination ID, the source ID, the PQI, the QoS characteristics, thePC5 SLRB configuration, and the PC5 SLRB ID, which are included in theAS configuration message received in operation 1553. In operation 1559,the UE1 1540 and the UE2 1560 may perform sidelink data transmission orreception by applying an AS configuration including the SLRBconfiguration.

Referring to FIG. 15C, a UE1 1570 and UE2 1590 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1571. Information exchanged between the two UEs 1570 and1590 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1570 and the UE2 1590 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1573. The UE1 1570 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1575. The UE2 1590 mayobtain an SLRB configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration, in operation 1577.For example, the SLRB configuration may include at least one or acombination of an RLC mode, a bi-directional RLC, a uni-directional RLC,a logical channel corresponding to the RLC mode, and an operationalparameter corresponding to the RLC mode. The SLRB configuration may beobtained through at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1579, the UE1 1570 may transmit an AS configuration messageto the UE2 1590 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1590. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

If the AS configuration message is received, the UE2 1590 may determinewhether the SLRB configuration obtained in operation 1577 collides withthe SLRB configuration included in the AS configuration message, inoperation 1581. A target parameter determining whether the SLRBconfigurations collide with each other may include at least one or acombination of an RLC mode (RLC AM or RLC UM), a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and a configuration parameter required for the operation of the RLCmode. If it is determined that the SLRB configurations collide with eachother in operation 1581, the UE2 1590 may identify information of aconfiguration parameter required to be adjusted due to a mismatch.

The UE2 1590 may transmit an AS configuration message including theinformation of the configuration parameter required to be adjusted, inoperation 1583. The AS configuration message of operation 1583 mayinclude information of a configuration parameter required to beadjusted, corresponding to the at least one or combination of the PC5flow ID, the destination ID, the source ID, the PQI, the QoScharacteristics, the PC5 SLRB configuration, and the PC5 SLRB ID, whichis received in operation 1579. The information of the configurationparameter required to be adjusted (or information of an adjustableconfiguration parameter) may include at least one of an adjustable RLCmode (RLC AM or RLC UM), a bi-directional RLC, a uni-directional RLC, alogical channel corresponding to the RLC mode, and a configurationparameter required for the operation of the RLC mode. The UE1 1570having received the AS configuration message of operation 1583 maydetermine whether the SLRB configuration is adjustable, based on theinformation of the configuration parameter (or information of anadjustable configuration parameter) of the AS configuration received inoperation 1583 (operation 1585).

If it is determined that the adjustment of the configuration parameteris not possible, the UE1 1570 may transmit an AS configuration completemessage including AS configuration failure indication information to theUE2 1590, in operation 1587. The AS configuration complete message mayinclude at least one or a combination of the PC5 flow ID, thedestination ID, the source ID, the PQI, the QoS characteristics, the PC5SLRB configuration, and the PC5 SLRB ID, which are included in the ASconfiguration message received in operation 1583.

In the embodiments illustrated in FIGS. 13, 14, 15A, 15B, and 15C, ifafter transmitting an AS configuration message, the UE1 fails to receivean AS configuration complete message from the UE2, or the UE1 receivesan AS configuration complete message indicating an AS configurationfailure from the UE2, the UE1 and the UE2 may not proceed with the ASconfiguration setup procedure any longer.

In the embodiment illustrated in FIGS. 15A, 15B, and 15C, if aftertransmitting an AS configuration message, the UE2 fails to receive an ASconfiguration complete message from the UE1, or the UE2 receives an ASconfiguration complete message indicating an AS configuration failurefrom the UE1, the UE1 and the UE2 may not proceed with the ASconfiguration setup procedure any longer.

According to various embodiments, if an initiating UE and/or a peer UEis an RRC Connected UE, an operation of determining and/or processing acollision of a bi-directional SLRB configuration parameter oruni-directional SLRB configuration parameter between the two UEs may beperformed using coordination between NWs of the UEs. For example, thepeer UE may transfer (report), to its own NW, bi-directional SLRBconfiguration information or uni-directional SLRB configurationinformation received from the initiating UE. The NW may determinewhether to accept and/or adjust the reported bi-directional SLRBconfiguration or uni-directional SLRB configuration, and may configure,for the peer UE, whether to accept the configuration, whether to adjustthe configuration, information of an adjustable parameter, and/orinformation of a parameter decided by being adjusted. The NW mayconfigure an SLRB configuration for the peer UE such that the SLRBconfiguration does not collide with the SLRB configuration of theinitiating UE.

For example, the NW may configure the same RLC mode. For example, the NWmay configure the same bi-directional RLC. For example, the NW mayconfigure the same uni-directional RLC. If it is determined to be hardto coordinate the SLRB configurations between the two UEs, the NW mayindicate an AS configuration failure to the peer UE. The peer UE maytransfer AS configuration failure indication information to theinitiating UE. The NW may determine information of a configurationparameter which can be coordinated between the two UEs. The NW maytransfer information of an adjustable configuration parameter to theinitiating UE through the peer UE.

The peer UE may transfer, to the initiating UE, whether to accept theconfiguration, whether to adjust the configuration, the information ofthe adjustable parameter, and/or the information of the parameterdecided by being adjusted, which are described above. The initiating UEmay report, to its own NW, information decided by being determined andprocessed by the NW of the peer UE. Information reported by theinitiating UE to its own NW may include whether the peer UE accepts thebi-directional SLRB configuration or uni-directional SLRB configuration,whether the peer UE adjusts the above configuration, information of anadjustable parameter, and/or information of a parameter decided by beingadjusted. If it is determined that the adjustment of a configurationparameter is possible, the initiating UE may configure a bi-directionalSLRB configuration or uni-directional SLRB configuration. If it isdetermined that the adjustment of the configuration parameter isimpossible, the initiating UE may determine an AS configuration failure.

FIG. 16A illustrates an SLRB configuration coordination method usingbase station cooperation according to various embodiments, FIG. 16Billustrates an SLRB configuration coordination method using base stationcooperation according to various embodiments, FIG. 17A illustrates aSLRB configuration coordination method using base station cooperationaccording to various embodiments, FIG. 17B illustrates a SLRBconfiguration coordination method using base station cooperationaccording to various embodiments, and FIG. 18 illustrates an SLRBconfiguration coordination method using base station cooperationaccording to various embodiments. The NW1s or NW2s illustrated in FIGS.16 to 18 may correspond to the same NWs or different NWs.

Referring to FIG. 16A, a UE1 1600 and UE2 1630 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1601. Information exchanged between the two UEs 1600 and1630 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1600 and the UE2 1630 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1603. The UE1 1600 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1605. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1607, the UE1 1600 may transmit an AS configuration messageto the UE2 1630 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1630. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

The UE2 1630 may transmit a PC5 SLRB configuration report message to anNW 1640 in order to obtain an SLRB configuration, in operation 1609. ThePC5 SLRB configuration report message may be replaced with aSidelinkUEInformation message or a UEAssistanceInformation message. ThePC5 SLRB configuration report message may include the at least one orcombination of the PC5 flow ID, the destination ID, the source ID, thePQI, the QoS characteristics, the PC5 SLRB configuration, and the PC5SLRB ID, which is received in operation 1607. PC5 SLRB configurationinformation reported by the above message may include at least one of anRLC mode (RLC AM or RLC UM), a bi-directional RLC, a uni-directionalRLC, a logical channel corresponding to the RLC mode, and aconfiguration parameter required for the operation of the RLC mode.

The NW 1640 may determine an SLRB configuration of the UE2 1630, basedon the information of the PC5 SLRB configuration report message. If itis determined to be possible to accept the SLRB configuration reportedin operation 1609, the NW 1640 may transmit, to the UE2 1630, a PC5 SLRBconfiguration confirm message as a response to the message received inoperation 1609, in operation 1611. The PC5 SLRB configuration confirmmessage may be replaced with an RRCReconfiguration message. The PC5 SLRBconfiguration confirm message may include at least one or combination ofinformation of an acknowledgement or failure for the SLRB configurationreported in operation 1609, a PC5 flow ID, a destination ID, a sourceID, a PQI, QoS characteristics, a PC5 SLRB configuration, and a PC5 SLRBID.

The UE2 1630 may determine the acquisition of the SLRB configurationfrom the NW 1640, in operation 1613, and may transmit an ASconfiguration complete message as a response to the AS configurationmessage of operation 1607 to the UE1 1600, in operation 1615. The ASconfiguration complete message may include at least one or a combinationof information corresponding to the AS configuration message, a PC5 flowID, a destination ID, a source ID, a PQI, and a PC5 SLRB ID. Inoperation 1617, the UE1 1600 and the UE2 1630 may perform sidelink datatransmission or reception by applying an AS configuration including theSLRB configuration.

Referring to FIG. 16B, a UE1 1650 and UE2 1680 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1651. Information exchanged between the two UEs 1650 and1680 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1650 and the UE2 1680 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1653. The UE1 1650 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1655. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1657, the UE1 1650 may transmit an AS configuration messageto the UE2 1680 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1680. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

The UE2 1680 may transmit a PC5 SLRB configuration report message to anNW 1690 in order to obtain an SLRB configuration, in operation 1659. ThePC5 SLRB configuration report message may be replaced with aSidelinkUEInformation message or a UEAssistanceInformation message. ThePC5 SLRB configuration report message may include the at least one orcombination of the PC5 flow ID, the destination ID, the source ID, thePQI, and the QoS characteristics, which is received in operation 1657.

The NW 1690 may determine an SLRB configuration of the UE2 1680, basedon information of the PC5 SLRB configuration report message. The NW 1690may transmit a PC5 SLRB configuration confirm message to the UE2 1680 asa response to operation 1659, in operation 1661. The PC5 SLRBconfiguration confirm message may be replaced with an RRCReconfigurationmessage. The PC5 SLRB configuration confirm message may include at leastone or a combination of a PC5 flow ID, a destination ID, a source ID, aPQI, QoS characteristics, a PC5 SLRB configuration, and a PC5 SLRB ID.The NW 1690 has a function of configuring a configuration parameter suchthat a collision between SLRB configurations, corresponding to at leastone or a combination of a PC5 flow ID, a destination ID, a source ID, aPQI, and QoS characteristics is prevented. For example, the NW 1690 mayadjust or control a collision related a bi-directional SLRBconfiguration parameter or a uni-directional SLRB configurationparameter by using a coordination procedure performed with another NW,or using a procedure of coordinating an SLRB configuration betweensystems related to the same PLMN, the same service provider, the sameregulation, or the same NW, as in the embodiment illustrated in FIG. 8 .

The UE2 1680 may determine the acquisition of the SLRB configurationfrom the NW 1690, in operation 1663, and may transmit an ASconfiguration complete message as a response to the AS configurationmessage of operation 1657 to the UE1 1650, in operation 1665. The ASconfiguration complete message may include at least one or a combinationof information corresponding to the AS configuration message, a PC5 flowID, a destination ID, a source ID, a PQI, and a PC5 SLRB ID. Inoperation 1667, the UE1 1650 and the UE2 1680 may perform sidelink datatransmission or reception by applying an AS configuration including theSLRB configuration.

Referring to FIG. 17A, a UE1 1700 and UE2 1730 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1701. Information exchanged between the two UEs 1700 and1730 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1700 and the UE2 1730 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1703. The UE1 1700 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1705. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1707, the UE1 1700 may transmit an AS configuration messageto the UE2 1730 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1730. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

The UE2 1730 may transmit a PC5 SLRB configuration report message to anNW 1740 in order to obtain an SLRB configuration, in operation 1709. ThePC5 SLRB configuration report message may be replaced with aSidelinkUEInformation message or a UEAssistanceInformation message. ThePC5 SLRB configuration report message may include the at least one orcombination of the PC5 flow ID, the destination ID, the source ID, thePQI, and the QoS characteristics, which is received in operation 1707.

The NW 1740 may determine an SLRB configuration of the UE2 1730, basedon information of the PC5 SLRB configuration report message. The NW 1740may transmit a PC5 SLRB configuration confirm message to the UE2 1730 asa response to operation 1709, in operation 1711. The PC5 SLRBconfiguration confirm message may be replaced with an RRCReconfigurationmessage. The PC5 SLRB configuration confirm message may include at leastone or a combination of a PC5 flow ID, a destination ID, a source ID, aPQI, QoS characteristics, a PC5 SLRB configuration, and a PC5 SLRB ID.

The UE2 1730 may determine the acquisition of the SLRB configurationfrom the NW 1740, in operation 1713. In operation 1713, the UE2 1730 mayidentify the SLRB configuration received in operation 1707 and the SLRBconfiguration obtained in operation 1711, to determine whether there isa collision of an SLRB configuration parameter. If it is determined thatthere is a collision of an SLRB configuration parameter, according tothe determination of operation 1713, the UE2 1730 may determine an ASconfiguration failure, and transmit an AS configuration complete messageto the UE1 1700 as a response to the AS configuration message ofoperation 1707, in operation 1715. The AS configuration complete messagemay include at least one or a combination of failure indicationinformation, and a PC5 flow ID, a destination ID, a source ID, a PQI,and a PC5 SLRB ID, which correspond to the AS configuration message. Ifthe AS configuration complete message indicates a failure, the ASconfiguration complete message may include information of the collidedSLRB configuration parameter. The information of the collided SLRBconfiguration parameter may include at least one or a combination of anRLC mode, a bi-directional RLC, a uni-directional RLC, a logical channelrelating to the RLC mode, and an RLC mode operational parameter.

If an AS configuration complete message including information indicatinga failure caused by a collision between the SLRB configurations isreceived, the UE1 1700 may determine that there is a collision betweenthe SLRB configurations (operation 1717). The UE1 1700 and the UE2 1730may recognize an AS configuration failure and may not proceed with theAS configuration procedure any longer.

The embodiment is described under the assumption that the UE2 1730 is anRRC Connected UE. If the UE2 1730 is an RRC Idle UE or an RRC InactiveUE, the UE2 may perform operation 1713, based on an SLRB configurationobtained by receiving an SIB message of the NW. If the UE2 1730 is anout-of-coverage UE, the UE2 may perform operation 1713, based on an SLRBconfiguration obtained from a preconfiguration.

Referring to FIG. 17B, a UE1 1750 and UE2 1780 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1751. Information exchanged between the two UEs 1750 and1780 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1750 and the UE2 1780 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1753. The UE1 1750 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1755. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1757, the UE1 1750 may transmit an AS configuration messageto the UE2 1780 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1780. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

The UE2 1780 may transmit a PC5 SLRB configuration report message to anNW 1790 in order to obtain an SLRB configuration, in operation 1759. ThePC5 SLRB configuration report message may be replaced with aSidelinkUEInformation message or a UEAssistanceInformation message. ThePC5 SLRB configuration report message may include the at least one orcombination of the PC5 flow ID, the destination ID, the source ID, thePQI, the QoS characteristics, the PC5 SLRB configuration, and the PC5SLRB ID, which is received in operation 1757. PC5 SLRB configurationinformation reported by the above message may include at least one of anRLC mode (RLC AM or RLC UM), a bi-directional RLC, a uni-directionalRLC, a logical channel corresponding to the RLC mode, and aconfiguration parameter required for the operation of the RLC mode.

The NW 1790 may determine an SLRB configuration of the UE2 1780, basedon the information of the PC5 SLRB configuration report message. If itis determined to be possible to accept the SLRB configuration reportedin operation 1759, the NW 1790 may transmit, to the UE2 1780, a PC5 SLRBconfiguration confirm message as a response to the message received inoperation 1759, in operation 1761. The PC5 SLRB configuration confirmmessage may be replaced with an RRCReconfiguration message. The PC5 SLRBconfiguration confirm message may include at least one or combination ofinformation of an acknowledgement or failure for the SLRB configurationreported in operation 1759, a PC5 flow ID, a destination ID, a sourceID, a PQI, QoS characteristics, a PC5 SLRB configuration, and a PC5 SLRBID.

If the SLRB configuration is received from the NW 1790, the UE2 1780 maytransmit an AS configuration complete message as a response to the ASconfiguration message of operation 1757 to the UE1 1750, in operation1763. If it is determined that SLRB configuration failure information isreceived from the NW 1790, the UE2 1780 may include, in the ASconfiguration complete message, at least one or a combination of a PC5flow ID, a destination ID, a source ID, a PQI, and a PC5 SLRB ID, whichcorresponds to the AS configuration message, and failure indicationinformation. If an AS configuration complete message includinginformation indicating a failure caused by a collision between the SLRBconfigurations is received, the UE1 1750 may determine that there is acollision between the SLRB configurations (operation 1765). The UE1 1750and the UE2 1780 may recognize an AS configuration failure and may notproceed with the AS configuration procedure any longer.

Referring to FIG. 18 , a UE1 1800 and UE2 1830 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 1801. Information exchanged between the two UEs 1800 and1830 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 1800 and the UE2 1830 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 1803. The UE1 1800 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 1805. For example, theSLRB configuration may include at least one or a combination of an RLCmode, a bi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and an operational parametercorresponding to the RLC mode. The SLRB configuration may be obtainedthrough at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 1807, the UE1 1800 may transmit an AS configuration messageto the UE2 1830 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 1830. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

The UE2 1830 may transmit a PC5 SLRB configuration report message to anNW2 1850 in order to obtain an SLRB configuration, in operation 1809.The PC5 SLRB configuration report message may be replaced with aSidelinkUEInformation message or a UEAssistanceInformation message. ThePC5 SLRB configuration report message may include the at least one orcombination of the PC5 flow ID, the destination ID, the source ID, thePQI, the QoS characteristics, the PC5 SLRB configuration, and the PC5SLRB ID, which is received in operation 1807. PC5 SLRB configurationinformation reported by the above message may include at least one or acombination of an RLC mode (RLC AM or RLC UM), a bi-directional RLC, auni-directional RLC, a logical channel corresponding to the RLC mode,and a configuration parameter required for the operation of the RLCmode.

The NW2 1850 may determine an SLRB configuration of the UE2 1830, basedon the information of the PC5 SLRB configuration report message. The NW21850 may determine whether to accept the SLRB configuration reported inoperation 1809, and if it is determined that there is a collision of anSLRB configuration parameter, the NW2 may identify an SLRB configurationparameter determined to be adjustable. The SLRB configuration parameterdetermined to be adjustable may include at least one of an RLC mode, abi-directional RLC, a uni-directional RLC, a logical channelcorresponding to the RLC mode, and a configuration parameter requiredfor the operation of the RLC mode. The NW2 1850 may transmit, to the UE21830, a PC5 SLRB configuration confirm message as a response to themessage received in operation 1809, in operation 1811. The PC5 SLRBconfiguration confirm message may be replaced with an RRCReconfigurationmessage. The PC5 SLRB configuration confirm message may include at leastone or combination of information of an acknowledgement or failure forthe SLRB configuration reported in operation 1811, information of anSLRB configuration parameter determined to be adjustable, a PC5 flow ID,a destination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

The UE2 1830 may determine the acquisition of the SLRB configurationfrom the NW2 1850. If the obtained SLRB configuration includesinformation of an SLRB configuration parameter that is adjustable, theUE2 1830 may configure an AS configuration message including theinformation of the adjustable SLRB configuration parameter and transmitthe message to the UE1 1800, in operation 1813. The AS configurationmessage of operation 1813 may include at least one or a combination of aPC5 flow ID, a destination ID, a source ID, a PQI, and a PC5 SLRB ID,which is information corresponding to the AS configuration message ofoperation 1807, and the information of the adjustable SLRB configurationparameter.

If the AS configuration message including the information of theadjustable SLRB configuration parameter is received, the UE1 1800 maydetermine that there is a collision between the SLRB configurations, inoperation 1815. The UE1 1800 may report the collision between the SLRBconfigurations to a NW1 1840 accessed by the UE1 itself. The UE1 1800may transmit a PC5 SLRB configuration report message, in operation 1817.The PC5 SLRB configuration report message may be replaced with aSidelinkUEInformation message or a UEAssistanceInformation message. ThePC5 SLRB configuration report message may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, a PC5 SLRB configuration, a PC5 SLRB ID, and anadjustable SLRB configuration parameter.

The UE1 1800 may receive a PC5 SLRB configuration confirm message fromthe NW1 1840, in operation 1819. The PC5 SLRB configuration confirmmessage may be replaced with an RRCReconfiguration message. The PC5 SLRBconfiguration confirm message may include at least one or a combinationof a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, a PC5 SLRB configuration, a PC5 SLRB ID, whether toapprove the adjustment of an SLRB configuration parameter, and anadjustable SLRB configuration parameter.

The UE1 1800 may transmit an AS configuration complete message to theUE2 1830 as a response to the message received in operation 1813, inoperation 1821. The AS configuration complete message may include atleast one or a combination of a PC5 flow ID, a destination ID, a sourceID, a PQI, QoS characteristics, a PC5 SLRB configuration, a PC5 SLRB ID,whether to approve the adjustment of an SLRB configuration parameter,and an adjustable SLRB configuration parameter.

When the adjustment of a PC5 SLRB configuration parameter is performedusing the NW1 1840 and the NW2 1850, the NW2 1850 may provide at leastone or a combination of an adjustable parameter set, an adjustableparameter, and a parameter to be adjusted, in the embodiment illustratedin FIG. 18 . The NW1 1840 may check whether at least one or combinationof the adjustable parameter set, the adjustable parameter, and theparameter to be adjusted is acceptable. If the adjustable parameter setis provided, the NW1 1840 may select one acceptable parameter. If theNW1 1840 determines that the adjustable parameter, or the parameter tobe adjusted is acceptable, the NW1 may indicate the approval of acorresponding adjustment parameter through AS configuration completesignaling transferred by the UE1 1800 to the UE2 1830. The UE2 1830 mayreport, to the NW2 1850, information relating to the failure oracknowledgement for the adjustment of a PC5 SLRB configuration, orrelating to which parameter has been adjusted.

In the embodiments illustrated in FIGS. 16A, 16B, 17A, 17B, and 18 , ifafter transmitting an AS configuration message, the UE1 fails to receivean AS configuration complete message from the UE2, or the UE1 receivesan AS configuration complete message indicating an AS configurationfailure from the UE2, the UE1 and the UE2 may not proceed with the ASconfiguration setup procedure any longer.

In the embodiment illustrated in FIG. 18 , if after transmitting an ASconfiguration message, the UE2 fails to receive an AS configurationcomplete message from the UE1, or the UE2 receives an AS configurationcomplete message indicating an AS configuration failure from the UE1,the UE1 and the UE2 may not proceed with the AS configuration setupprocedure any longer.

FIG. 19 is a signal flow diagram for processing SLRB configurationprocessing failure according to various embodiments.

Referring to FIG. 19 , a UE1 1900 may determine an AS configurationsetup failure caused by a collision of an SLRB configuration to beapplied to a sidelink unicast connection with an opponent UE, inoperation 1901. The UE1 1900 corresponds to at least one of aninitiating UE, a peer UE, or a designated UE.

The UE1 1900 may transmit a PC5 SLRB configuration report message to anNW3 1940 of the UE1 itself, in operation 1903. The PC5 SLRBconfiguration report message may be used to notify that an SLRBconfiguration obtained from the NW3 1940 and an SLRB configurationreceived from the opponent UE mismatch. The PC5 SLRB configurationreport message may include at least one or a combination of a PQI, PC5QoS characteristics, a PC5 flow ID, a PC5 SLRB ID, a destination ID, anda source ID, which are obtained from the NW3 1940. The PC5 SLRBconfiguration report message may include information of a configurationparameter determined to be mismatched, among SLRB configurationparameters corresponding to the PQI, the PC5 QoS characteristics, thePC5 flow ID, the PC5 SLRB ID, the destination ID, and the source ID (Forexample, the information is at least one of an RLC mode, abi-directional RLC, a uni-directional RLC, information of a logicalchannel corresponding to the RLC mode, and an operational parametercorresponding to the RLC mode).

The NW3 1940 may perform a sidelink configuration informationcoordination operation together with an NW4 1950 illustrated in FIG. 19, which is another NW, based on the information received from the PC5SLRB configuration report, in operation 1905. Information exchangedbetween the NW3 1940 and the NW4 1950 in the sidelink configurationinformation coordination operation may include at least one of an RLCmode, a bi-directional RLC, a uni-directional RLC, information of alogical channel for each RLC mode, and an operational parameter for eachRLC mode, corresponding to at least one of a PQI, PC5 QoScharacteristics, a PC5 flow ID, a PC5 SLRB ID, a destination ID, and asource ID. The coordination operation between the NWs in operation 1905may be performed to configure the same SLRB configuration for at leastone or a combination of the same PQI, PC5 QoS characteristics,destination ID, source ID, PC5 SLRB ID, and PC5 flow ID between the NWs.

According to various embodiments, if an initiating UE and/or a peer UEis an RRC Inactive UE, an RRC Idle UE, or an Out-of-coverage UE, anoperation of determining and/or processing a collision of an SLRBconfiguration parameter between the two UEs may correspond to at leastone or a combination of the embodiments illustrated in FIG. 10A, FIG. 10b , FIG. 11 , FIG. 12 , FIG. 13 , FIG. 14 , FIG. 15A, FIG. 15B, and FIG.15C.

According to various embodiments, an operation of determining andprocessing a mismatch between SLRB configurations in consideration of anSLRB-configuration designated UE selected by the method illustrated inFIG. 9 may employ the embodiment illustrated in FIG. 10A or 10B. Thedesignated UE may perform the same operation as that of the initiatingUE, illustrated in FIG. 10A or 10B. The designated UE may perform anoperation of obtaining a bi-directional SLRB configuration or auni-directional SLRB configuration, and transferring the obtainedconfiguration to the opponent UE.

In another embodiment, the designated UE may perform an operation ofdetermining whether there is a mismatch between an SLRB configurationobtained by the designated UE itself, and an SLRB configuration receivedfrom the opponent, and processing the resultant mismatch or match. Thedesignated UE may perform the same operation as that of the peer UE,illustrated in FIG. 13, 14, 15B, 16, 17 , or 18, and may perform anoperation of transferring, to the opponent UE, at least one ofinformation of a match/mismatch, adjustment information relating to aconfiguration parameter determined to be mismatched, and adjustedconfiguration parameter information relating to a mismatchedconfiguration parameter. If the designated UE is an RRC Connected UE,the designated UE may perform at least one or a combination of theoperations of: obtaining an SLRB configuration from an NW, reportinginformation of an SLRB configuration received from the opponent UE, tothe NW, so as to identify the SLRB configuration; obtaining informationof a mismatched configuration parameter from the NW; obtaininginformation of an adjustable configuration parameter from the NW; andobtaining adjusted SLRB configuration information from the NW.

If it is determined to be necessary to coordinate configurationinformation of an SLRB configuration between the UE1 and the UE2 asillustrated in FIG. 15A, 15B, 15C, or 18, the UE2 may provide, to theUE1, at least one or a combination of an RLC mode, a bi-directional RLC,a uni-directional RLC, a logical channel applicable to the RLC mode, andan operational parameter of the RLC mode, as an SLRB configurationparameter required to be adjusted. For example, a method for notifyingof an applicable logical channel may use at least one of one or multiplelogical channel values which are available, one or multiple logicalchannel values which are being used, and a bitmap of logical channelinformation which is available or being used.

FIG. 20 is a signal flow diagram between UEs processing a collisionbetween SLRB configurations according to various embodiments. Theembodiment illustrated in FIG. 20 shows a signal procedure in which UEshaving determined a collision between SLRB configurations determine touse a default SLRB configuration for a sidelink unicast connection, andexchange information relating to the configuration.

Referring to FIG. 20 , a UE1 2000 and UE2 2030 may perform a PC5signaling procedure for configuring a sidelink-based unicast connection,in operation 2001. Information exchanged between the two UEs 2000 and2030 in the PC5 signaling procedure may include at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, QoScharacteristics, and a PC5 unicast ID. The UE1 2000 and the UE2 2030 mayperform a sidelink UE capability information exchange procedure in a PC5RRC connection procedure, in operation 2003. The UE1 2000 may obtain anSLRB configuration including a bi-directional SLRB configuration oruni-directional SLRB configuration, in operation 2005. The UE2 2030 mayobtain an SLRB configuration including a bi-directional SLRBconfiguration or uni-directional SLRB configuration, in operation 2007.For example, the SLRB configuration may include at least one or acombination of an RLC mode, a bi-directional RLC, a uni-directional RLC,a logical channel corresponding to the RLC mode, and an operationalparameter corresponding to the RLC mode. The SLRB configuration may beobtained through at least one of a dedicated RRC message, an SIB, and apreconfiguration.

In operation 2009, the UE1 2000 may transmit an AS configuration messageto the UE2 2030 to perform an AS configuration procedure in the PC5 RRCconnection procedure together with the UE2 2030. The AS configurationmessage may include at least one or a combination of a PC5 flow ID, adestination ID, a source ID, a PQI, QoS characteristics, a PC5 SLRBconfiguration, and a PC5 SLRB ID.

If the AS configuration message is received, the UE2 2030 may determinewhether the SLRB configuration obtained in operation 2007 collides withthe SLRB configuration included in the AS configuration message, inoperation 2011. A target parameter determining whether the SLRBconfigurations collide with each other may include at least one ofconfiguration parameters of RLC mode operations in addition to an RLCmode (RLC AM or RLC UM), a bi-directional RLC, a uni-directional RLC, alogical channel corresponding to the RLC mode, and the like.

If it is determined that the SLRB configurations collide with each otherin operation 2011, the UE 2 2030 may determine an AS configurationfailure, and transfer an AS configuration complete message to the UE12000 as a response to the AS configuration message received in operation2009, in operation 2013. The AS configuration complete message mayinclude at least one or a combination of information corresponding tothe AS configuration message, a PC5 flow ID, a destination ID, a sourceID, a PQI, a PC5 SLRB ID, failure indication information, and defaultSLRB configuration use indication information. For example, the UE2 2030may include, in the AS configuration complete message, information of aparameter causing the collision between the SLRB configurations. If theAS configuration complete message including AS configuration failureindication and default SLRB configuration indication information isreceived from the UE2 2030, the UE1 2000 may determine use of a defaultSLRB configuration for a sidelink unicast corresponding to at least oneor a combination of the PC5 flow ID, the destination ID, the source ID,and the PQI (operation 2015).

The UE1 2000 may transmit an AS configuration complete messagecorresponding to the message of operation 2013 to the UE2 2030 inoperation 2017. The AS configuration complete message transmitted inoperation 2017 may include at least one or a combination of a PC5 flowID, a destination ID, a source ID, a PQI, and default SLRB configurationindication information. In operation 2019, the UE1 2000 and the UE2 2030may perform sidelink data transmission or reception by applying adefault SLRB configuration.

Another embodiment may use a procedure in which the UE1 2000 maytransmit an AS configuration message including at least one or acombination of a PC5 flow ID, a destination ID, a source ID, a PQI, anddefault SLRB configuration indication information, in operation 2017,and the UE2 2030 transmits an AS configuration complete message as anresponse to the AS configuration message transmitted by the UE1 2000.After the procedure of transmission and reception of the ASconfiguration message and the AS configuration complete message, the UE12000 and the UE2 2030 may perform sidelink data transmission orreception by applying a default SLRB configuration.

Methods disclosed in the claims and/or methods according to variousembodiments described in the specification of the disclosure may beimplemented by hardware, software, or a combination of hardware andsoftware.

When the methods are implemented by software, a computer-readablestorage medium for storing one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin the electronic device. The at least one program may includeinstructions that cause the electronic device to perform the methodsaccording to various embodiments of the disclosure as defined by theappended claims and/or disclosed herein.

The programs (software modules or software) may be stored innon-volatile memories including a random access memory and a flashmemory, a read only memory (ROM), an electrically erasable programmableread only memory (EEPROM), a magnetic disc storage device, a compactdisc-ROM (CD-ROM), digital versatile discs (DVDs), or other type opticalstorage devices, or a magnetic cassette. Alternatively, any combinationof some or all of them may form a memory in which the program is stored.Further, a plurality of such memories may be included in the electronicdevice.

In addition, the programs may be stored in an attachable storage devicewhich may access the electronic device through communication networkssuch as the Internet, Intranet, Local Area Network (LAN), Wide LAN(WLAN), and Storage Area Network (SAN) or a combination thereof. Such astorage device may access the electronic device via an external port.Further, a separate storage device on the communication network mayaccess a portable electronic device.

In the above-described detailed embodiments of the disclosure, anelement included in the disclosure is expressed in the singular or theplural according to presented detailed embodiments. However, thesingular form or plural form is selected appropriately to the presentedsituation for the convenience of description, and the disclosure is notlimited by elements expressed in the singular or the plural. Therefore,either an element expressed in the plural may also include a singleelement or an element expressed in the singular may also includemultiple elements.

Although specific embodiments have been described in the detaileddescription of the disclosure, various modifications and changes may bemade thereto without departing from the scope of the disclosure.Therefore, the scope of the disclosure should not be defined as beinglimited to the embodiments, but should be defined by the appended claimsand equivalents thereof.

Although the present disclosure has been described with variousembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a first terminal in awireless communication system, the method comprising: receiving, from asecond terminal, a first message including a first sidelink radio bearer(SLRB) configuration; identifying whether a failure of an access stratum(AS) configuration associated with bi-directional sidelink connectionoccurs based on whether first information included in the first SLRBconfiguration collides with second information included in a second SLRBconfiguration of the first terminal; and transmitting, to the secondterminal, a second message including information indicating the failureof the AS configuration, in case that the failure of the ASconfiguration is identified, wherein the first information correspondsto a radio link control (RLC) mode of a logical channel configured basedon the first SLRB configuration and the second information correspondsto an RLC mode of a logical channel configured based on the second SLRBconfiguration.
 2. The method of claim 1, further comprising:transmitting, to the second terminal, a third message includinginformation indicating application of the first SLRB configuration, incase that the failure of the AS configuration is not identified based onthe RLC mode of the logical channel included in the first SLRBconfiguration.
 3. The method of claim 1, wherein the failure of the ASconfiguration is identified based on the RLC mode of the logical channelincluded in the first SLRB configuration received from the secondterminal and another RLC mode of a logical channel received from a basestation.
 4. The method of claim 1, wherein sidelink terminal informationis transmitted from the second terminal to a base station based on thefailure of the AS configuration, and wherein the sidelink terminalinformation includes the RLC mode of the logical channel included in thefirst SLRB configuration and information indicating the failure of theAS configuration.
 5. The method of claim 4, wherein a radio resourcecontrol (RRC) reconfiguration message including a new SLRB configurationassociated with the first SLRB configuration is transmitted from thebase station to the second terminal as a response to the sidelinkterminal information, and wherein the sidelink terminal informationfurther includes a sidelink destination identity associated with thefailure of the AS configuration.
 6. A method performed by a secondterminal in a wireless communication system, the method comprising:transmitting, to a first terminal, a first message including a firstsidelink radio bearer (SLRB) configuration; receiving, from the firstterminal, a second message as a response to the first message; andidentifying a failure of an access stratum (AS) configuration associatedwith bi-directional sidelink connection in case that the second messagecorresponds to a message including information indicating the failure ofthe AS configuration, wherein whether the failure of the ASconfiguration associated with bi-directional sidelink connection occursis determined based on whether first information included in the firstSLRB configuration collides with second information included in a secondSLRB configuration of the first terminal, and wherein the firstinformation corresponds to a radio link control (RLC) mode of a logicalchannel configured based on the first SLRB configuration and the secondinformation corresponds to an RLC mode of a logical channel configuredbased on the second SLRB configuration.
 7. The method of claim 6,further comprising: identifying the first SLRB configuration is appliedto the first terminal, in case that the second message corresponds to amessage including information indicating application of the first SLRBconfiguration.
 8. The method of claim 6, transmitting, to a basestation, sidelink terminal information including the informationindicating the failure of the AS configuration and the RLC mode of thelogical channel included in the first SLRB configuration, in case thatthe failure of the AS configuration is identified; and receiving, fromthe base station, a radio resource control (RRC) reconfiguration messageincluding a new SLRB configuration associated with the first SLRBconfiguration as a response to the sidelink terminal information.
 9. Themethod of claim 8, wherein the sidelink terminal information furtherincludes a sidelink destination identity associated with the failure ofthe AS configuration.
 10. The method of claim 6, wherein a timer isstarted as a response to a transmission of the first message, andwherein the timer is stopped as a response to a reception of the secondmessage.
 11. A first terminal in a wireless communication system, thefirst terminal comprising: a transceiver; and a controller configuredto: receive, from a second terminal via the transceiver, a first messageincluding sidelink radio bearer (SLRB) configuration, identify whether afailure of an access stratum (AS) configuration associated withbi-directional sidelink connection is occurred based on whether firstinformation included in the first SLRB configuration collides withsecond information included in a second SLRB configuration of the firstterminal, and transmit, to the second terminal via the transceiver, asecond message including information indicating the failure of the ASconfiguration, in case that the failure of the AS configuration isidentified, wherein the first information corresponds to a radio linkcontrol (RLC) mode of a logical channel configured based on the firstSLRB configuration and the second information corresponds to an RLC modeof a logical channel configured based on the second SLRB configuration.12. The first terminal of claim 11, wherein the controller is configuredto transmit, to the second terminal via the transceiver, a third messageincluding information indicating application of the first SLRBconfiguration, in case that the failure of the AS configuration is notidentified based on the RLC mode of the logical channel included in thefirst SLRB configuration.
 13. The first terminal of claim 11, whereinthe failure of the AS configuration is identified based on the RLC modeof the logical channel included in the first SLRB configuration receivedfrom the second terminal and another RLC mode of a logical channelreceived from a base station.
 14. The first terminal of claim 11,wherein sidelink terminal information is transmitted from the secondterminal to a base station based on the failure of the AS configuration,and wherein the sidelink terminal information includes the RLC mode ofthe logical channel included in the first SLRB configuration andinformation indicating the failure of the AS configuration.
 15. Thefirst terminal of claim 14, wherein a radio resource control (RRC)reconfiguration message including a new SLRB configuration associatedwith the first SLRB configuration is transmitted from the base stationto the second terminal as a response to the sidelink terminalinformation, and wherein the sidelink terminal information furtherincludes a sidelink destination identity associated with the failure ofthe AS configuration.
 16. A second terminal in a wireless communicationsystem, the second terminal comprising: a transceiver; and a controllerconfigured to: transmit, to a first terminal via the transceiver, afirst message including a sidelink radio bearer (SLRB) configuration,receive, from the first terminal via the transceiver, a second messageas a response to the second message, and identify a failure of an accessstratum (AS) configuration associated with bi-directional sidelinkconnection in case that the second message corresponds to a messageincluding information indicating the failure of the AS configuration,wherein whether the failure of the AS configuration associated withbi-directional sidelink connection occurs is determined based on whetherfirst information included in the first SLRB configuration collides withsecond information included in a second SLRB configuration of the firstterminal, and wherein the first information corresponds to a radio linkcontrol (RLC) mode of a logical channel configured based on the firstSLRB configuration and the second information corresponds to an RLC modeof a logical channel configured based on the second SLRB configuration.17. The second terminal of claim 16, wherein the controller is furtherconfigured to identify the first SLRB configuration is applied to thefirst terminal, in case that the second message corresponds to a messageincluding information indicating application of the first SLRBconfiguration.
 18. The second terminal of claim 16, wherein thecontroller is configured to: transmit, to a base station via thetransceiver, sidelink terminal information including the informationindicating the failure of the AS configuration and the RLC mode of thelogical channel included in the first SLRB configuration, in case thatthe failure of the AS configuration is identified, and receive, from thebase station via the transceiver, a radio resource control (RRC)reconfiguration message including a new SLRB configuration associatedwith the first SLRB configuration as a response to the sidelink terminalinformation.
 19. The second terminal of claim 18, wherein the sidelinkterminal information further includes a sidelink destination identityassociated with the failure of the AS configuration.
 20. The secondterminal of claim 16, wherein a timer is started as a response to atransmission of the first message, and wherein the timer is stopped as aresponse to a reception of the second message.